A374273 a(n) is the smallest number which can be represented as the sum of three distinct nonzero n-gonal numbers in exactly n ways, or -1 if no such number exists.

37, 161, 498, 1666, 2546, 7434, 16609, 25952, 48786, 49861, 72347, 127335, 183289, 196469, 416913, 466546, 494369, 506649, 801010, 1401011, 2372586, 1414009, 2003027, 3274986, 2927260, 2721677, 5592756, 8016592, 6632759, 7057914, 8401837, 13248146, 11648679, 8650006

Offset

3,1

Links

Table of n, a(n) for n=3..36.

Eric Weisstein's World of Mathematics, Polygonal Number

Example

a(3) = 37 = 1 + 15 + 21 = 3 + 6 + 28 = 6 + 10 + 21.
a(4) = 161 = 1^2 + 4^2 + 12^2 = 2^2 + 6^2 + 11^2 = 4^2 + 8^2 + 9^2 = 5^2 + 6^2 + 10^2.

Crossrefs

Cf. A025415, A057145, A350405, A374144, A374274.

Sequence in context: A140011 A296156 A250842 * A083389 A142909 A269259

Adjacent sequences: A374270 A374271 A374272 * A374274 A374275 A374276

Keyword

nonn

Author

Ilya Gutkovskiy, Jul 02 2024

Extensions

a(21) and beyond from Michael S. Branicky, Jul 08 2024

Status

approved