A366867 Products of sexy prime triples: sphenic numbers with prime factorization (p - 6)*p*(p + 6).

935, 1729, 4301, 11339, 49321, 102131, 146969, 298351, 386389, 1089019, 1221191, 3864241, 5171489, 12640949, 16965341, 18181979, 21243961, 43974269, 51881689, 178433279, 208506509, 223626691, 230324329, 270816731, 278421569, 393806449, 849244031, 932539661

Offset

1,1

Links

Matthew Goers, Table of n, a(n) for n = 1..1000

Formula

a(n) = (A006489(n) - 6)*A006489(n)*(A006489(n) + 6).

Example

5, 11, and 17 are primes p, p+6, p+12, called a sexy prime triple. 5*11*17 = 935, so 935 is a term.
7, 13, and 19 are the second set of sexy prime triples. 7*13*19=1729, so 1729 is the second term.

Mathematica

(#*(#^2 - 36)) & /@ Select[Prime[Range[180]], PrimeQ[# - 6] && PrimeQ[# + 6] &] (* Amiram Eldar, Oct 27 2023 *)

Prog

(PARI) apply(x->x*(x-6)*(x+6), select(x->(isprime(x-6) && isprime(x) && isprime(x+6)), [1..1000])) \\ Michel Marcus, Oct 27 2023

Crossrefs

Cf. A006489, A111192. Subsequence of A007304.

Sequence in context: A347852 A171348 A232380 * A292571 A029570 A278186

Adjacent sequences: A366864 A366865 A366866 * A366868 A366869 A366870

Keyword

nonn

Author

Matthew Goers, Oct 25 2023

Status

approved