%I #4 Oct 22 2018 12:01:37
%S 1,1,4,11,26,55,106,190,321,518,804,1207,1763,2511,3502,4794,6447,
%T 8541,11163,14407,18382,23215,29040,36005,44284,54059,65529,78918,
%U 94466,112434,133104,156783,183803,214518,249307,288580,332774,382358,437829,499717,568579
%N Number of 6-element subsets of [n] whose sum is a triangular number.
%H Alois P. Heinz, <a href="/A320852/b320852.txt">Table of n, a(n) for n = 6..1000</a>
%Y Column k=6 of A284249.
%Y Cf. A000217.
%K nonn
%O 6,3
%A _Alois P. Heinz_, Oct 22 2018
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