A106571 Indices n of perfect squares n^2 which are not the difference of two primes.

5, 7, 11, 13, 17, 19, 23, 25, 27, 29, 31, 35, 37, 41, 43, 47, 49, 51, 53, 55, 59, 61, 63, 65, 67, 69, 71, 73, 75, 77, 79, 83, 85, 87, 89, 91, 93, 95, 97, 101, 103, 107, 109, 113, 115, 119, 121, 125, 127, 129, 131, 133, 135, 137, 139, 141, 143, 145, 149, 151, 153, 155

Offset: 1

Author

Alexandre Wajnberg, May 09 2005

Keywords

• easy
• nonn

Comments

Also, n such that 1+n^2 is a nontotient (A005277). - T. D. Noe, Sep 13 2007

Examples

			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).
		

Links

• T. D. Noe, Table of n, a(n) for n=1..1000

Crossrefs

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

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

Formula

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

Extensions

Extended by Ray Chandler, May 12 2005