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A247171 G.f.: (2*x^2+4*x+3)/((2*x+2)*sqrt(-4*x^3-4*x^2+1))-1/(2*x+2). 0
1, 1, 3, 4, 11, 21, 48, 106, 235, 535, 1203, 2751, 6272, 14392, 33078, 76224, 176043, 407253, 943833, 2190397, 5090371, 11843689, 27586793, 64320191, 150102784, 350586496, 819477792, 1916861350, 4486760870, 10508582130, 24626700888 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..30.

FORMULA

a(n) = n*sum(k=1..n, (binomial(2*k,n-k)*binomial(n-k-1,k-1))/k, n>0, a(0)=1.

MATHEMATICA

CoefficientList[Series[(2 x^2 + 4 x + 3) / ((2 x + 2) Sqrt[-4 x^3 - 4 x^2 + 1]) - 1 / (2 x + 2), {x, 0, 40}], x] (* Vincenzo Librandi, Nov 22 2014 *)

PROG

(Maxima)

a(n):=if n=0 then 1 else n*sum((binomial(2*k, n-k)*binomial(n-k-1, k-1))/k, k, 1, n);

CROSSREFS

Cf. A007477.

Sequence in context: A152982 A001642 A001643 * A005218 A219514 A131481

Adjacent sequences:  A247168 A247169 A247170 * A247172 A247173 A247174

KEYWORD

nonn

AUTHOR

Vladimir Kruchinin, Nov 22 2014

STATUS

approved

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Last modified December 5 10:45 EST 2019. Contains 329751 sequences. (Running on oeis4.)