a(n) = Sum_{k=0..n-1} (105k+44)*C(2k,k)^2*T(k)*(-1)^(n-1-k)/(2n*C(2n,n)), where T(k) (k=0,1,2,...) are central trinomial coefficients given by A002426.

A181147

a(n) = Sum_{k=0..n-1} (105k+44)*C(2k,k)^2*T(k)*(-1)^(n-1-k)/(2n*C(2n,n)), where T(k) (k=0,1,2,...) are central trinomial coefficients given by A002426.

Terms

    a(0) =11a(1) =23a(2) =224a(3) =1747a(4) =16754a(5) =162392a(6) =1651206a(7) =17126327a(8) =181182446a(9) =1943132842a(10) =21080299228a(11) =230802972664

External references