cp's OEIS Frontend

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

%I A276809 #14 Sep 22 2016 07:02:22
%S A276809 7,17,11,13,23,53,67,37,47,59,61,73,83,173,281,107,353,367,269,283,
%T A276809 293,157,167,179,193,607,617,641,653,227,509,263,547,277,1193,907,313,
%U A276809 653,1669,347,359,1087,383,773,787,397,421,1783,907,457,467,479,1447,503,1543
%N A276809 Least prime p such that (p^2-1)/24 is divisible by prime(n) or 0 if no such prime exists.
%C A276809 Sequence motivated by a comment in A024702: "The set of prime factors of a(n), however, appears to include all primes".
%H A276809 Seiichi Manyama, <a href="/A276809/b276809.txt">Table of n, a(n) for n = 1..10000</a>
%e A276809 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).
%e A276809 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).
%e A276809 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).
%o A276809 (PARI) a(n) = {p = prime(n); q = prime(3); while (! vecsearch(factor((q^2 - 1)/24)[,1], p), q = nextprime(q+1)); q;}
%Y A276809 Cf. A024702.
%K A276809 nonn
%O A276809 1,1
%A A276809 _Michel Marcus_, Sep 18 2016