Sum ((-1)^(i+1)*binomial(n,i)*2^i*(2*i-1)!,i=1..n).

A006547

Sum ((-1)^(i+1)*binomial(n,i)*2^i*(2*i-1)!,i=1..n).

Terms

    a(0) =0a(1) =2a(2) =-20a(3) =894a(4) =-76936a(5) =11218330a(6) =-2486192988a(7) =779417002070

External references