A374274 a(n) is the smallest number which can be represented as the sum of four distinct nonzero n-gonal numbers in exactly n ways, or -1 if no such number exists.

47, 142, 344, 652, 834, 1542, 2263, 3090, 4792, 4570, 5844, 8480, 9571, 10542, 15892, 18202, 19587, 23166, 26732, 32040, 36371, 39730, 44709, 52940, 55141, 60362, 67705, 79624, 86906, 89266, 103591, 116246, 126610, 131462, 135324, 148190, 158152, 162422, 186126, 200254

Offset

3,1

Links

Michael S. Branicky, Table of n, a(n) for n = 3..204

Eric Weisstein's World of Mathematics, Polygonal Number

Example

a(3) = 47 = 1 + 3 + 15 + 28 = 1 + 10 + 15 + 21 = 3 + 6 + 10 + 28.
a(4) = 142 = 1^2 + 2^2 + 4^2 + 11^2 = 1^2 + 4^2 + 5^2 + 10^2 = 2^2 + 5^2 + 7^2 + 8^2 = 3^2 + 4^2 + 6^2 + 9^2.

Crossrefs

Cf. A025417, A057145, A350405, A374144, A374273.

Sequence in context: A212374 A040984 A136070 * A055822 A044379 A044760

Adjacent sequences: A374271 A374272 A374273 * A374275 A374276 A374277

Keyword

nonn

Author

Ilya Gutkovskiy, Jul 02 2024

Extensions

a(36) and beyond from Michael S. Branicky, Jul 08 2024

Status

approved