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 A288255 Number of nonagons that can be formed with perimeter n. 10
 1, 1, 2, 3, 5, 7, 11, 14, 21, 28, 39, 50, 69, 87, 116, 145, 189, 233, 299, 363, 458, 553, 687, 820, 1009, 1195, 1453, 1709, 2058, 2404, 2872, 3331, 3948, 4557, 5361, 6152, 7194, 8215, 9547, 10853, 12543, 14199, 16329, 18407, 21067, 23666, 26964, 30179, 34248, 38207 (list; graph; refs; listen; history; text; internal format)
 OFFSET 9,3 COMMENTS Number of (a1, a2, ... , a9) where 1 <= a1 <= ... <= a9 and a1 + a2 + ... + a8 > a9. LINKS Seiichi Manyama, Table of n, a(n) for n = 9..10000 G. E. Andrews, P. Paule and A. Riese, MacMahon's Partition Analysis IX: k-gon partitions, Bull. Austral Math. Soc., 64 (2001), 321-329. Index entries for linear recurrences with constant coefficients, signature (0, 1, 0, 1, 0, 0, 0, 0, 1, -1, -1, 0, -1, -1, 0, 0, 0, -1, 1, 0, 0, 1, 1, 2, 0, 1, 1, 0, 0, 1, -1, -1, -2, -1, -1, -2, 0, -1, -1, -1, 1, 1, 1, 0, 2, 1, 1, 2, 1, 1, -1, 0, 0, -1, -1, 0, -2, -1, -1, 0, 0, -1, 1, 0, 0, 0, 1, 1, 0, 1, 1, -1, 0, 0, 0, 0, -1, 0, -1, 0, 1). FORMULA G.f.: x^9/((1-x)*(1-x^2)* ... *(1-x^9)) - x^16/(1-x) * 1/((1-x^2)*(1-x^4)* ... *(1-x^16)). a(2*n+16) = A026815(2*n+16) - A288343(n), a(2*n+17) = A026815(2*n+17) - A288343(n) for n >= 0. - Seiichi Manyama, Jun 08 2017 CROSSREFS Number of k-gons that can be formed with perimeter n: A005044 (k=3), A062890 (k=4), A069906 (k=5), A069907 (k=6), A288253 (k=7), A288254 (k=8), this sequence (k=9), A288256 (k=10). Sequence in context: A051014 A035968 A112581 * A325853 A035976 A035985 Adjacent sequences:  A288252 A288253 A288254 * A288256 A288257 A288258 KEYWORD nonn,easy AUTHOR Seiichi Manyama, Jun 07 2017 STATUS approved

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Last modified August 5 22:40 EDT 2021. Contains 346488 sequences. (Running on oeis4.)