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A112353 Triangular numbers that are the sum of three distinct positive triangular numbers. 2
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 (list; graph; refs; listen; history; text; internal format)
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: A031105 A302529 A054501 * A031077 A082286 A088407

Adjacent sequences:  A112350 A112351 A112352 * A112354 A112355 A112356

KEYWORD

nonn

AUTHOR

Rick L. Shepherd, Sep 05 2005

STATUS

approved

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Last modified October 23 16:46 EDT 2019. Contains 328373 sequences. (Running on oeis4.)