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A196924 Smallest prime(k) such that prime(k+n) + prime(k) is a perfect square. 1

%I

%S 17,5,2,3,61,7,83,2,173,29,11,43,1019,2,89,3,83,397,11,47,2,101,3,17,

%T 131,13,167,59,7,83,5,193,73,17,233,67,179,2,29,5,167,3,83,47,17,43,2,

%U 41,293,101,5,137,53,281,773,17,857,13,41,11,383,7,439,503

%N Smallest prime(k) such that prime(k+n) + prime(k) is a perfect square.

%e a(5) = 61 is the smallest initial prime of a subset of 6 consecutive primes {61, 67, 71, 73, 79, 83} such that 83 + 61 = 144 = 12^2.

%p A196924:= proc(n)

%p for k from 1 do

%p if issqr(ithprime(k+n)+ithprime(k)) then

%p return ithprime(k);

%p end if;

%p end do:

%p end proc:

%p seq(A196924(n), n=1..80) ;

%Y Cf. A000040, A196874, A196815.

%K nonn

%O 1,1

%A _Michel Lagneau_, Oct 07 2011

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Last modified July 31 08:38 EDT 2021. Contains 346369 sequences. (Running on oeis4.)