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 A103872 a(n) = 3*trinomial(n+1,0) - trinomial(n+2,0). 1
 0, 2, 2, 6, 12, 30, 72, 182, 464, 1206, 3170, 8426, 22596, 61074, 166194, 454950, 1251984, 3461574, 9611190, 26787378, 74916660, 210178458, 591347988, 1668172842, 4717282752, 13369522250, 37970114702, 108045430902 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS First differs from A059727 for n = 8. LINKS Eric Weisstein's World of Mathematics, Trinomial Coefficient MAPLE trinomial := n -> simplify(GegenbauerC(n, -n, -1/2)): a := n -> 3*trinomial(n+1) - trinomial(n+2): seq(a(n), n=0..27); # Peter Luschny, May 07 2016 MATHEMATICA Table[(4*2^n (2n + 3)!! (3 Hypergeometric2F1[-2 - n, -1 - n, -3/2 - n, 1/4] - 4 Hypergeometric2F1[-2 - n, -2 - n, -3/2 - n, 1/4]))/(n + 2)!, {n, 0, 20}] (* Vladimir Reshetnikov, May 07 2016 *) CROSSREFS Cf. A059727. Sequence in context: A088219 A027375 A059727 * A216641 A191970 A175516 Adjacent sequences:  A103869 A103870 A103871 * A103873 A103874 A103875 KEYWORD nonn,easy AUTHOR Eric W. Weisstein, Feb 19 2005 STATUS approved

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Last modified February 23 16:14 EST 2020. Contains 332173 sequences. (Running on oeis4.)