Thursday, December 27, 2012
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. A twin prime is a prime number that differs from another prime number by two.
43 is the smallest prime that is not a Chen prime. A prime number p is called a Chen prime if p + 2 is either a prime or a product of two primes (also called semiprimes).
43 is the fourth term of Sylvester's sequence, one more than the product of the previous terms (2 × 3 × 7). Sylvester's sequence is an integer sequence in which each member of the sequence is the product of the previous members, plus one.
43 is a centered heptagonal number. A centered heptagonal number is a centered figurate number that represents a heptagon with a dot in the center and all other dots surrounding the center dot in successive heptagonal layers.
43 is a repdigit in base 6 (111). A repdigit is a natural number composed of repeated instances of the same digit, most often in the decimal numeral system.
On the whole, a largely unremarkable number.