A276809 Least prime p such that (p^2-1)/24 is divisible by prime(n) or 0 if no such prime exists.

7, 17, 11, 13, 23, 53, 67, 37, 47, 59, 61, 73, 83, 173, 281, 107, 353, 367, 269, 283, 293, 157, 167, 179, 193, 607, 617, 641, 653, 227, 509, 263, 547, 277, 1193, 907, 313, 653, 1669, 347, 359, 1087, 383, 773, 787, 397, 421, 1783, 907, 457, 467, 479, 1447, 503, 1543

Offset

1,1

Comments

Sequence motivated by a comment in A024702: "The set of prime factors of a(n), however, appears to include all primes".

Links

Seiichi Manyama, Table of n, a(n) for n = 1..10000

Example

a(1) = 7 because 7 is the least prime p such that (p^2-1)/24, which is 2, is divisible by 2=prime(1).
a(2) = 17 because 17 is the least prime p such that (p^2-1)/24, which is 12, is divisible by 3=prime(2).
a(3) = 11 because 11 is the least prime p such that (p^2-1)/24, which is 5, is divisible by 5=prime(3).

Prog

(PARI) a(n) = {p = prime(n); q = prime(3); while (! vecsearch(factor((q^2 - 1)/24)[, 1], p), q = nextprime(q+1)); q; }

Crossrefs

Cf. A024702.

Sequence in context: A138449 A156680 A107804 * A274916 A128713 A283163

Adjacent sequences: A276806 A276807 A276808 * A276810 A276811 A276812

Keyword

nonn

Author

Michel Marcus, Sep 18 2016

Status

approved