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 A226253 Number of ways of writing n as the sum of 9 triangular numbers. 16
 1, 9, 36, 93, 198, 378, 633, 990, 1521, 2173, 2979, 4113, 5370, 6858, 8955, 11055, 13446, 16830, 20031, 23724, 28836, 33381, 38520, 45729, 52203, 59121, 68922, 77461, 86283, 99747, 110547, 121500, 138870, 152034, 166725, 188568, 204156, 221760, 248310, 268713, 289422, 321786, 345570, 369036 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS Seiichi Manyama, Table of n, a(n) for n = 0..10000 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. FORMULA G.f. is 9th power of g.f. for A010054. a(0) = 1, a(n) = (9/n)*Sum_{k=1..n} A002129(k)*a(n-k) for n > 0. - Seiichi Manyama, May 06 2017 G.f.: exp(Sum_{k>=1} 9*(x^k/k)/(1 + x^k)). - Ilya Gutkovskiy, Jul 31 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: A162258 A128642 A342252 * A340965 A022604 A085630 Adjacent sequences:  A226250 A226251 A226252 * A226254 A226255 A226256 KEYWORD nonn AUTHOR N. J. A. Sloane, Jun 01 2013 STATUS approved

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Last modified April 13 01:36 EDT 2021. Contains 342934 sequences. (Running on oeis4.)