%I #67 Dec 21 2018 16:35:45

%S 0,1,6,7,15,21,22,28,43,45,49,50,66,73,88,91,94,95,111,120,139,153,

%T 154,157,160,161,190,202,211,230,231,245,251,252,273,276,277,322,325,

%U 343,350,364,365,371,372,378,421,430,435,463,475,496,503,507,518,524,525,554,561

%N Numbers that are sums of consecutive hexagonal numbers (A000384).

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/HexagonalNumber.html">Hexagonal Number</a>

%t anmax = 1000; nmax = Floor[Sqrt[anmax/2]] + 1; Select[Union[Flatten[Table[Sum[k*(2*k-1), {k, i, j}], {i, 0, nmax}, {j, i, nmax}]]], # <= anmax &] (* _Vaclav Kotesovec_, Dec 21 2018 *)

%Y Cf. A000384, A002412, A034705, A034706, A319184, A322636, A322637.

%K nonn

%O 1,3

%A _Ilya Gutkovskiy_, Dec 21 2018