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.
Let a0 = a1 = 1, and thenceforth an = 1/(a02 + a12 + ... + an − 12). This sequence continues 1, 1, 2, 3, 5, 10, 28, 154... (sequence A003504 in the OEIS). a43 is the first term of this sequence that is not an integer.
43 is the largest prime which dives the order of the Janko group J4.
43 is a repdigit in base 6 (111).
43 is the number of triangles inside the Sri Yantra.
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.
- 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.
- 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 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 until 2016, and, through the 2012 season, the Nationwide Series.
Arts, entertainment, and media
- 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.
- Number 43, in Sonnets from the Portuguese (1850), is one of Elizabeth Barrett Browning's most famous poems.
In other fields
- +43, the code for direct dial international phone calls to Austria.
- Bush 43, George W. Bush, 43rd President of the United States.
- "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.[importance?]
- 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
- 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.]
- 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