A202948 a(n+1) = 3*A136016*a(n).

-3, -72, -7560, -1814400, -778377600, -523069747200, -506854585036800, -669048052248576000, -1154107890128793600000, -2520571632041285222400000, -6797981691615346244812800000

Offset

1,1

Comments

Sums of coefficients from (3n+2)th moments of binomial(m,k)*binomial(2m,k): see Maple code below.

Links

Table of n, a(n) for n=1..11.

Eric W. Weisstein, MathWorld: Binomial Sums

Formula

a(n)=-(1/6)*27^n*GAMMA(n-1/3)*GAMMA(n+1/3)*sqrt(3)/Pi.

Example

The evaluation of sum(k^8 binomial(n,k) binomial(2n,k), k=0..n) involves the polynomial 64n^10 + 192n^9 - 1344n^8 - 1056n^7 + 8256n^6 - 3696n^5 - 9940n^4 + 7551n^3 + 348n^2 - 507n + 60, the sum of the coefficients of which is -72=a(2).

Maple

with(PolynomialTools); polyn := proc (q) options operator, arrow; 3^q*Pi*GAMMA(2*n)*(sum(k^q*binomial(n, k)*binomial(2*n, k), k = 0 .. n))/(27^n*sqrt(3)*GAMMA(n-floor((1/3)*q+1/3)+2/3)*GAMMA(n-floor((1/3)*q)+1/3)) end proc; coefl := proc (q) options operator, arrow; CoefficientList(expand(polyn(q)), n) end proc; coe := proc (j, h) options operator, arrow; coefl(j)[h] end proc; seq(sum(coe(3*r+2, k), k = 1 .. 5*r+3), r = 1 .. 8) ;

Prog

(PARI) print1(a=-3); for(n=2, 20, print1(", ", a*=27*n*(n-2)+24)) \\ Charles R Greathouse IV, Dec 27 2011

Crossrefs

Cf. A136016, A064350.

Sequence in context: A300967 A332721 A332747 * A213986 A156908 A182517

Adjacent sequences: A202945 A202946 A202947 * A202949 A202950 A202951

Keyword

sign,easy

Author

John M. Campbell, Dec 26 2011

Status

approved