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A276809 Least prime p such that (p^2-1)/24 is divisible by prime(n) or 0 if no such prime exists. 1
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified March 31 03:48 EDT 2020. Contains 333136 sequences. (Running on oeis4.)