This article may contain indiscriminate, excessive, or irrelevant examples. (March 2010) |

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Cardinal | forty-three | |||

Ordinal | 43rd (forty-third) | |||

Factorization | prime | |||

Prime | 14th | |||

Divisors | 1, 43 | |||

Greek numeral | ΜΓ´ | |||

Roman numeral | XLIII | |||

Binary | 101011_{2} | |||

Ternary | 1121_{3} | |||

Quaternary | 223_{4} | |||

Quinary | 133_{5} | |||

Senary | 111_{6} | |||

Octal | 53_{8} | |||

Duodecimal | 37_{12} | |||

Hexadecimal | 2B_{16} | |||

Vigesimal | 23_{20} | |||

Base 36 | 17_{36} |

**43** (**forty-three**) is the natural number following 42 and preceding 44.

## Contents

## In mathematics

Forty-three is the 14th smallest prime number. The previous is forty-one, with which it comprises a twin prime, and the next is forty-seven. 43 is the smallest prime that is not a Chen prime. It is also the third Wagstaff prime.^{[1]}

43 is the fourth term of Sylvester's sequence, one more than the product of the previous terms (2 × 3 × 7).^{[2]}

43 is a centered heptagonal number.^{[3]}

Let *a*_{0} = *a*_{1} = 1, and thenceforth *a*_{n} = 1/*n* − 1(*a*_{0}^{2} + *a*_{1}^{2} + ... + *a*_{n − 1}^{2}). This sequence continues 1, 1, 2, 3, 5, 10, 28, 154... (sequence A003504 in the OEIS). *a*_{43} is the first term of this sequence that is not an integer.

43 is a Heegner number.^{[4]}

43 is the largest prime which dives the order of the Janko group J_{4}.

43 is a repdigit in base 6 (111).

43 is the largest natural number that is not a (original) McNugget number.^{[5]}

43 is the smallest prime number expressible as the sum of 2, 3, 4, or 5 different primes:

- 43 = 41 + 2
- 43 = 11 + 13 + 19
- 43 = 2 + 11 + 13 + 17
- 43 = 3 + 5 + 7 + 11 + 17.

When taking the first six terms of the Taylor series for computing e, one obtains

which is also five minus the fifth harmonic number.

Every solvable configuration of the Fifteen puzzle can be solved in no more than 43 multi-tile moves (i.e. when moving two or three tiles at once is counted as one move).^{[6]}

## In science

- The chemical element with the atomic number 43 is technetium. It has the lowest atomic number of any element that does not possess stable isotopes.

### Astronomy

- Messier object M43, a magnitude 7.0 H II region in the constellation of Orion, a part of the Orion Nebula, and also sometimes known as
*de Mairan's Nebula* - The New General Catalogue object NGC 43, a barred spiral galaxy in the constellation Andromeda

## In sports

In auto racing:

- The number for Richard Petty's race car when he won his seven Winston Cup Championships. He also won 200 races in his career, 95% of them in the famous #43.
- The maximum number of cars participating in a NASCAR race in the Cup Series, and, through the 2012 season, the Nationwide Series.

## Arts, entertainment, and media

### Music

- The number of notes in Harry Partch's 43-tone scale of just intonation.

### Popular culture

*Movie 43*(2013) is a film consisting of a series of interconnected short stories, featuring some of the biggest stars in Hollywood, which make up the insane storylines a washed-up producer is pitching to a movie company.- In
*The Big Bang Theory*episode "The 43 Peculiarity", Howard and Raj try to solve the mystery of Sheldon disappearing every afternoon to a room with a chalkboard that has the number 43 written on it. - In
*Odd Squad*, Agent 43 is one of the main villains, Agent Todd. The number 43 is also a recurring Easter egg throughout the series.^{[7]}^{[unreliable source]}

### Literature

- Number 43, in
*Sonnets from the Portuguese*(1850), is one of Elizabeth Barrett Browning's most famous poems.

## In other fields

Forty-three is:

- +43, the code for direct dial international phone calls to Austria.
- Bush 43, George W. Bush, 43rd President of the United States.
^{[8]} - "43", a song by Level 42 on the album
*Level 42*. - "43," a song by metal band Mushroomhead on the albums "Mushroomhead" and "XX"
- U.S.S. Coral Sea CV-43 (aircraft carrier).
- The name of a popular Spanish liqueur, Cuarenta y tres, which is distilled with 43 different herbs and spices.
- In the lyrics of at least two operas: W. S. Gilbert's
*Trial by Jury*and Lorenzo Da Ponte's*Le nozze di Figaro*.^{[citation needed]}^{[importance?]}

## See also

## Notes

**^**Sloane, N. J. A. (ed.). "Sequence A000979 (Wagstaff primes)".*The On-Line Encyclopedia of Integer Sequences*. OEIS Foundation. Retrieved 2016-05-30.**^**Sloane, N. J. A. (ed.). "Sequence A000058 (Sylvester's sequence)".*The On-Line Encyclopedia of Integer Sequences*. OEIS Foundation. Retrieved 2016-05-30.**^**Sloane, N. J. A. (ed.). "Sequence A069099 (Centered heptagonal numbers)".*The On-Line Encyclopedia of Integer Sequences*. OEIS Foundation. Retrieved 2016-05-30.**^**Sloane, N. J. A. (ed.). "Sequence A003173 (Heegner numbers)".*The On-Line Encyclopedia of Integer Sequences*. OEIS Foundation. Retrieved 2016-05-30.**^**Sloane, N. J. A. (ed.). "Sequence A065003 (Not McNugget numbers)".*The On-Line Encyclopedia of Integer Sequences*. OEIS Foundation. Retrieved 2016-05-30.**^**"The Fifteen Puzzle can be solved in 43 "moves"". Domain of the Cube Forum**^**"43".*Odd Squad Wiki*. Retrieved 2019-02-14.**^**Kellogg, William O. (2010).*Barron's AP United States History*(9th ed.). Barron's Educational Series. p. 364. ISBN 9780764141843.*George H. W. Bush*(Republican) [Bush 41—i.e., the first president Bush, George H. W. Bush was the forty-first President of the United States, and so some have referred to him in this way since the election of his son, George W. Bush or Bush 43—the forty-third president of the United States.]

## References

- Lehmer, Derrick,
*List of prime numbers from 1 to 10,006,721*, Carnegie Institution of Washington, 1914 - Wells, David,
*Prime Numbers: The Most Mysterious Figures in Math*, Wiley, 2005, ISBN 0-471-46234-9 - Crandall, Richard and Pomerance, Carl,
*Prime Numbers: A Computational Perspective*, Springer, 2005, ISBN 0-387-25282-7 - http://www.espncricinfo.com/south-africa-v-sri-lanka-2011/content/current/story/548918.html