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Indices n of perfect squares n^2 which are not the difference of two primes.
18

%I #13 Mar 14 2018 06:54:43

%S 5,7,11,13,17,19,23,25,27,29,31,35,37,41,43,47,49,51,53,55,59,61,63,

%T 65,67,69,71,73,75,77,79,83,85,87,89,91,93,95,97,101,103,107,109,113,

%U 115,119,121,125,127,129,131,133,135,137,139,141,143,145,149,151,153,155

%N Indices n of perfect squares n^2 which are not the difference of two primes.

%C Also, n such that 1+n^2 is a nontotient (A005277). - _T. D. Noe_, Sep 13 2007

%H T. D. Noe, <a href="/A106571/b106571.txt">Table of n, a(n) for n=1..1000</a>

%F a(n) = sqrt(A106564(n)).

%e a(3)=11 because the third square which is not the difference of two primes (121=11^2) is the 11th one in the succession of the perfect squares (thus index 11).

%Y Cf. A106544-A106548, A106562-A106564, A106573-A106575, A106577.

%Y Cf. A067201 (n such that n^2 + 2 is prime).

%K easy,nonn

%O 1,1

%A _Alexandre Wajnberg_, May 09 2005

%E Extended by _Ray Chandler_, May 12 2005