A320855 Number of 9-element subsets of [n] whose sum is a triangular number.

1, 1, 6, 21, 64, 174, 419, 930, 1921, 3741, 6933, 12303, 21044, 34839, 56044, 87885, 134682, 202181, 297873, 431423, 615166, 864673, 1199421, 1643537, 2226716, 2985188, 3962845, 5212562, 6797615, 8793297, 11288719, 14388852, 18216738, 22915930, 28653268

Offset

9,3

Links

Alois P. Heinz, Table of n, a(n) for n = 9..1000

Crossrefs

Column k=9 of A284249.

Cf. A000217.

Sequence in context: A321947 A291226 A228704 * A319613 A117962 A105457

Adjacent sequences: A320852 A320853 A320854 * A320856 A320857 A320858

Keyword

nonn

Author

Alois P. Heinz, Oct 22 2018

Status

approved