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A320851
Number of 5-element subsets of [n] whose sum is a triangular number.
2
1, 1, 4, 9, 18, 35, 61, 100, 156, 235, 342, 482, 664, 895, 1185, 1542, 1977, 2505, 3134, 3879, 4757, 5782, 6968, 8337, 9909, 11699, 13732, 16030, 18615, 21514, 24755, 28361, 32362, 36789, 41673, 47051, 52953, 59412, 66466, 74158, 82525, 91611, 101454, 112097
OFFSET
5,3
LINKS
CROSSREFS
Column k=5 of A284249.
Cf. A000217.
Sequence in context: A333394 A301150 A301078 * A027053 A122039 A083706
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Oct 22 2018
STATUS
approved