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
Keywords
Examples
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.
Links
- Eric Weisstein's World of Mathematics, Polygonal Number
Extensions
a(21) and beyond from Michael S. Branicky, Jul 08 2024