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 A173000 a(n) = binomial(n + 4, 4)*9^n. 8
 1, 45, 1215, 25515, 459270, 7440174, 111602610, 1578379770, 21308126895, 277005649635, 3490271185401, 42835146366285, 514021756395420, 6049640671423020, 70002984912180660, 798034027998859524 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Number of n-permutations (n>=4) of 10 objects p, r, q, u, v, w, z, x, y, z with repetition allowed, containing exactly 4 u's. LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..400 Index entries for linear recurrences with constant coefficients, signature (45,-810,7290,-32805,59049). FORMULA G.f.: 1/(1-9*x)^5. - R. J. Mathar, Dec 21 2011 a(n) = 45*a(n-1)-810*a(n-2)+7290*a(n-3)-32805*a(n-4)+59049*a(n-5). - Wesley Ivan Hurt, Apr 21 2021 MAPLE A173000:=n->binomial(n+4, 4)*9^n: seq(A173000(n), n=0..25); # Wesley Ivan Hurt, Jul 24 2017 MATHEMATICA Table[Binomial[n + 4, 4]*9^n, {n, 0, 20}] PROG (MAGMA) [Binomial(n+4, 4)*9^n: n in [0..20]]; // Vincenzo Librandi, Oct 13 2011 (PARI) a(n)=binomial(n+4, 4)*9^n \\ Charles R Greathouse IV, Oct 07 2015 CROSSREFS Sequence in context: A229796 A143400 A226981 * A004350 A199518 A075515 Adjacent sequences:  A172997 A172998 A172999 * A173001 A173002 A173003 KEYWORD nonn,easy AUTHOR Zerinvary Lajos, Feb 07 2010 STATUS approved

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Last modified December 6 22:42 EST 2021. Contains 349567 sequences. (Running on oeis4.)