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A051945 a(n) = C(n)*(5n+1) where C(n) = Catalan numbers (A000108). 5

%I

%S 1,6,22,80,294,1092,4092,15444,58630,223652,856596,3292016,12688732,

%T 49031400,189885240,736808220,2863971270,11149451940,43465121700,

%U 169657266240,662976162420

%N a(n) = C(n)*(5n+1) where C(n) = Catalan numbers (A000108).

%D A. H. Beiler, Recreations in the Theory of Numbers, Dover, N.Y., 1964, pp. 194-196.

%F (n+1)*(5n-4)*a(n) - 2*(5n+1)(2n-1)*a(n-1) = 0. - _R. J. Mathar_, Jul 09 2012

%F G.f.: (2 - 3*x - 2*sqrt(1 - 4*x))/(x*sqrt(1 - 4*x)). - _Ilya Gutkovskiy_, Jun 13 2017

%o (PARI) a(n) = (5*n+1)*binomial(2*n, n)/(n+1) \\ _Michel Marcus_, Jul 12 2013

%Y Cf. A016813, A000108, A051924.

%K easy,nonn

%O 0,2

%A _Barry E. Williams_, Dec 20 1999

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Last modified October 21 20:44 EDT 2019. Contains 328315 sequences. (Running on oeis4.)