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A161491 a(n) = number of primes p less than A000040(n) (the n-th prime) such that (p + 1)*(A000040(n) - 1) is a square 0

%I #3 Jan 26 2014 15:37:09

%S 0,0,1,1,0,2,1,2,0,0,1,1,0,1,0,0,0,1,0,0,4,0,0,0,3,1,1,0,4,0,1,0,0,1,

%T 0,4,0,6,0,0,0,3,0,5,1,1,0,0,0,1,0,0,2,1,1,0,0,2,0,0,1,0,0,0,1,0,0,1,

%U 0,1,1,0,0,0,2,0,0,1,1,1,0,1,0,6,0,0,1,1,0,1,0,0,6,2,0,0,0,0,1,2,0,0,0,0,1

%N a(n) = number of primes p less than A000040(n) (the n-th prime) such that (p + 1)*(A000040(n) - 1) is a square

%o (PARI) forprime(q=1,1000,my(q1=q-1,c=0);forprime(p=1,q-1,issquare((p+1)*q1)&c++);print1(c",")) - _M. F. Hasler_

%K nonn

%O 1,6

%A _Creighton Dement_, Jun 11 2009

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Last modified April 25 12:28 EDT 2024. Contains 371969 sequences. (Running on oeis4.)