A112353 Triangular numbers that are the sum of three distinct positive triangular numbers.

10, 28, 45, 55, 66, 91, 105, 120, 136, 153, 171, 190, 210, 231, 253, 276, 300, 325, 351, 378, 406, 435, 465, 496, 528, 561, 595, 630, 666, 703, 741, 780, 820, 861, 903, 946, 990, 1035, 1081, 1128, 1176, 1225, 1275, 1326, 1378, 1431, 1485

Offset

1,1

Comments

Subsequence of A112355: it doesn't require the three positive triangular numbers to be distinct.

Links

Table of n, a(n) for n=1..47.

Example

45 is a term because 45 = 3 + 6 + 36 and these four numbers are distinct triangular numbers (A000217(9) = A000217(2) + A000217(3) + A000217(8)).

Mathematica

trnos=Accumulate[Range[200]];
Take[Union[Select[Total/@Subsets[trnos, {3}], MemberQ[trnos, #]&]], 50]  (* Harvey P. Dale, Jan 15 2011 *)

Crossrefs

Cf. A000217 (triangular numbers), A112352 (triangular numbers that are the sum of two distinct positive triangular numbers), A112355.

Sequence in context: A356456 A302529 A054501 * A031077 A082286 A088407

Adjacent sequences: A112350 A112351 A112352 * A112354 A112355 A112356

Keyword

nonn

Author

Rick L. Shepherd, Sep 05 2005

Status

approved