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A226252 Number of ways of writing n as the sum of 7 triangular numbers. 15
1, 7, 21, 42, 77, 126, 175, 253, 357, 434, 567, 735, 833, 1057, 1302, 1400, 1708, 2037, 2191, 2597, 3003, 3151, 3619, 4242, 4389, 4935, 5691, 5740, 6594, 7434, 7371, 8400, 9303, 9506, 10626, 11592, 11585, 12761, 14427, 14203, 15519, 17241, 16808, 18788, 20559, 19950, 21882, 23898, 23786 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

REFERENCES

K. Ono, S. Robins and P. T. Wahl, On the representation of integers as sums of triangular numbers, Aequationes mathematicae, August 1995, Volume 50, Issue 1-2, pp 73-94; http://www.math.wisc.edu/~ono/reprints/006.pdf.

LINKS

Seiichi Manyama, Table of n, a(n) for n = 0..10000

FORMULA

G.f. is 7th power of g.f. for A010054.

a(0) = 1, a(n) = (7/n)*Sum_{k=1..n} A002129(k)*a(n-k) for n > 0. - Seiichi Manyama, May 06 2017

CROSSREFS

Number of ways of writing n as a sum of k triangular numbers, for k=1,...: A010054, A008441, A008443, A008438, A008439, A008440, A226252, A007331, A226253, A226254, A226255, A014787, A014809.

Sequence in context: A205864 A162818 A024966 * A022602 A054569 A077354

Adjacent sequences:  A226249 A226250 A226251 * A226253 A226254 A226255

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Jun 01 2013

STATUS

approved

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Last modified May 23 16:47 EDT 2017. Contains 286925 sequences.