A287166 Smallest number with exactly n representations as a sum of 7 nonzero squares or 0 if no such number exists.

7, 22, 31, 37, 45, 67, 55, 61, 69, 70, 79, 82, 94, 108, 85, 93, 103, 106, 111, 132, 109, 126, 139, 117, 147, 146, 130, 145, 144, 133, 153, 167, 141, 154, 160, 172, 159, 166, 187, 157, 177, 174, 175, 0, 178, 165

Offset: 1

Author

Ilya Gutkovskiy, May 20 2017

Keywords

• nonn

Examples

			a(1) = 7 because 7 is the smallest number with exactly 1 representation as a sum of 7 nonzero squares: 7 = 1^2 + 1^2 + 1^2 + 1^2 + 1^2 + 1^2 + 1^2;
a(2) = 22 because 22 is the smallest number with exactly 2 representations as a sum of 7 nonzero squares: 22 = 1^2 + 1^2 + 1^2 + 1^2 + 1^2 + 1^2 + 4^2 = 1^2 + 1^2 + 2^2 + 2^2 + 2^2 + 2^2 + 2^2, etc.
		

Links

• Eric Weisstein's World of Mathematics, Square Number
• Index entries for sequences related to sums of squares

Crossrefs

Cf. A016032, A025414, A025416, A025431, A080654, A287165, A287167.

Formula

A025431(a(n)) = n for a(n) > 0.