A274255 Numbers n such that n^2 is the sum of three nonzero squares while n is not.

7, 13, 15, 23, 25, 28, 31, 37, 39, 47, 52, 55, 58, 60, 63, 71, 79, 85, 87, 92, 95, 100, 103, 111, 112, 119, 124, 127, 130, 135, 143, 148, 151, 156, 159, 167, 175, 183, 188, 191, 199, 207, 208, 215, 220, 223, 231, 232, 239, 240, 247, 252, 255, 263, 271, 279, 284

Offset: 1

Author

Altug Alkan, Jun 16 2016

Keywords

• nonn
• easy

Examples

			7 is a term because 7 is not in A000408 and 7^2 = 49 = 2^2 + 3^2 + 6^2.
		

Crossrefs

Cf. A000408, A005767.

Programs

PARI

isA000408(n) = my(a, b) ; a=1 ; while(a^2+1A000408(n) && isA000408(n^2), print1(n, ", ")));