# 43 (number)

 ← 42 43 44 →
Cardinal forty-three
Ordinal 43rd
(forty-third)
Factorization prime
Divisors 1, 43
Roman numeral XLIII
Binary 1010112
Ternary 11213
Quaternary 2234
Octal 538
Duodecimal 3712
Vigesimal 2320
Base 36 1736

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

## 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.

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

43 is a centered heptagonal number.

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

43 is a Heegner number.

43 is a repdigit in base 6 (111).

43 is the largest natural number that is not an (original) McNugget number.

 4 15 17 7 5 19 13 6 20 9 2 12 14 0 11 18

This 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 date magic square at right illustrates the magic constant as the sum of four primes:

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

$\sum_{i=0}^{5}\frac{1}{i!}=\frac{163}{60}=2+\frac{43}{60},\$

which is also five minus the fifth harmonic number.

## In sports

In the US's National Football League, the number 43 was worn by Jim Norton of the Tennessee Titans (formerly the Houston Oilers). The Titans have retired the number.

In auto racing:

• Brad Daugherty, ESPN NASCAR analyst and retired American basketball player. His #43 jersey, a number he picked as a tribute to NASCAR legend Richard Petty (whom Daugherty lists as his favorite sportsman), was retired by the Cavaliers on March 1, 1997.

In Ice Hockey:

In baseball:

In cricket:

• Sri Lanka's lowest ODI score ever made chasing 302 to win against South Africa (January 11, 2012)

## Films

In a film by Pixar called Cars, the champion racecar in the film, Strip "The King" Wheathers is racecar number 43 based on Richard Petty's car. Petty also provides the voice of "The King" in the film.

In season 6 episode 8 of The Big Bang Theory 43 is a number discovered on a black board in a room where Sheldon Cooper spends 20 minutes a day to "rest" from various activities occupying his mind. The room was discovered by Raj and Howard when they were following Sheldon to figure out what he did within the 20 minute empty span in his schedule. Raj and Howard thought of many scientific explanations for the number when in reality the number only represented Sheldon's Hacky Sacking high score.

## In other fields

Forty-three is:

• The designation of Interstate 43, a freeway in Wisconsin.
• +43, the code for direct dial international phone calls to Austria.
• Bush 43, George W. Bush, 43rd President of the United States.[1]
• "43", a song by Level 42 on the album Level 42.