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A138462 A bisection of A006318. 2
1, 6, 90, 1806, 41586, 1037718, 27297738, 745387038, 20927156706, 600318853926, 17518619320890, 518431875418926, 15521467648875090, 469286147871837366, 14308406109097843626, 439442782615614361662, 13582285614213903189954, 422158527806921249683014 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Colin Barker, Table of n, a(n) for n = 0..300

FORMULA

a(n) = Sum_{i=0..2n} (C(2*n+1,i+1)*C(2*n+i,i))/(2*n+1). - Vladimir Kruchinin, Apr 02 2017

PROG

(Maxima)

a(n):=sum(binomial(2*n+1, i+1)*binomial(2*n+i, i), i, 0, 2*n)/(2*n+1); /* Vladimir Kruchinin, Apr 02 2017 */

(PARI) a(n) = sum(i=0, 2*n, binomial(2*n+1, i+1)*binomial(2*n+i, i))/(2*n+1) \\ Colin Barker, Dec 28 2017

CROSSREFS

Sequence in context: A247150 A201073 A006480 * A002896 A266734 A004996

Adjacent sequences:  A138459 A138460 A138461 * A138463 A138464 A138465

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane, May 08 2008

STATUS

approved

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Last modified October 23 12:10 EDT 2018. Contains 316527 sequences. (Running on oeis4.)