A118565 Numbers which are both lucky and triangular.

1, 3, 15, 21, 105, 171, 231, 741, 903, 1275, 1485, 1711, 2211, 2415, 3003, 3403, 3655, 4095, 4465, 4851, 5151, 5253, 5671, 7503, 8001, 8515, 10153, 10585, 10731, 11781, 13203, 13695, 13861, 17391, 18145, 18915, 19503, 21115, 22155, 22791, 24531

Offset

1,2

Links

Donovan Johnson, Table of n, a(n) for n = 1..3537

Mathematica

triQ[n_] := IntegerQ@Sqrt[8n+1]; lst = Range[1, 26564, 2]; i = 2; While[ i <= (len = Length@lst) && (k = lst[[i]]) <= len, lst = Drop[lst, {k, len, k}]; i++ ]; Select[lst, triQ@# &] (* Robert G. Wilson v *)

Crossrefs

Cf. A000959, A000217.

Sequence in context: A350987 A076825 A259745 * A230658 A117801 A347303

Adjacent sequences: A118562 A118563 A118564 * A118566 A118567 A118568

Keyword

nonn

Author

Luc Stevens (lms022(AT)yahoo.com), May 07 2006

Extensions

Corrected and extended by Adam Panagos (adam.panagos(AT)gmail.com) and Robert G. Wilson v, May 10 2006

Status

approved