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 A275874 a(n) = (n-4)*(n+1)*(n+3)/6. 3
 0, 8, 21, 40, 66, 100, 143, 196, 260, 336, 425, 528, 646, 780, 931, 1100, 1288, 1496, 1725, 1976, 2250, 2548, 2871, 3220, 3596, 4000, 4433, 4896, 5390, 5916, 6475, 7068, 7696, 8360, 9061, 9800, 10578, 11396, 12255, 13156, 14100, 15088, 16121, 17200, 18326, 19500, 20723, 21996 (list; graph; refs; listen; history; text; internal format)
 OFFSET 4,2 LINKS Colin Barker, Table of n, a(n) for n = 4..1000 Hilton, Peter John, and Jean Pedersen, Descartes, Euler, Poincaré, Pólya and Polyhedra, L'Enseign. Math., 27 (1981), 327-343. See Cor. 1. Index entries for linear recurrences with constant coefficients, signature (4,-6,4,-1). FORMULA From Colin Barker, Aug 15 2016: (Start) a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - a(n-4) for n > 7. G.f.: x^5*(8 - 11*x + 4*x^2) / (1 - x)^4. (End) MAPLE a := n -> (n - 4)*(n + 1)*(n + 3)/6: seq(a(n), n = 4..51); # Peter Luschny, Jan 25 2019 PROG (PARI) concat(0, Vec(x^5*(8-11*x+4*x^2)/(1-x)^4 + O(x^50))) \\ Colin Barker, Aug 15 2016 CROSSREFS A137742 is an essentially identical sequence. Sequence in context: A000567 A124484 A137742 * A190456 A188026 A180672 Adjacent sequences:  A275871 A275872 A275873 * A275875 A275876 A275877 KEYWORD nonn,easy AUTHOR N. J. A. Sloane, Aug 14 2016 STATUS approved

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Last modified June 19 12:54 EDT 2021. Contains 345129 sequences. (Running on oeis4.)