A363253 a(n) is the smallest n-gonal number which can be represented as the sum of distinct nonzero n-gonal numbers in exactly n ways, or -1 if no such number exists.

28, 121, 210

Offset

3,1

Comments

a(8) = 736, a(9) = 969.

Links

Table of n, a(n) for n=3..5.

Eric Weisstein's World of Mathematics, Polygonal Number

Example

For n = 3: 1 + 6 + 21 = 3 + 10 + 15 = 28.

Crossrefs

Cf. A057145, A350207, A350405, A350423.

Sequence in context: A220755 A244079 A330533 * A101095 A232403 A219851

Adjacent sequences: A363250 A363251 A363252 * A363254 A363255 A363256

Keyword

nonn,bref,more,hard

Author

Ilya Gutkovskiy, May 23 2023

Status

approved