A106571 - OEIS

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

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OFFSET

1,1

COMMENTS

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

LINKS

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

FORMULA

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

EXAMPLE

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).

CROSSREFS

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

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

Sequence in context: A322271 A306289 A136801 * A067291 A286265 A339911

Adjacent sequences: A106568 A106569 A106570 * A106572 A106573 A106574

KEYWORD

easy,nonn

AUTHOR

Alexandre Wajnberg, May 09 2005

EXTENSIONS

Extended by Ray Chandler, May 12 2005

STATUS

approved