a(n) = [x^n] 2 / (1 - (2*n - 1)*x + sqrt(1 - 2*x - 3*x^2)).

A344556

a(n) = [x^n] 2 / (1 - (2*n - 1)*x + sqrt(1 - 2*x - 3*x^2)).

Terms

    a(0) =1a(1) =1a(2) =5a(3) =34a(4) =315a(5) =3741a(6) =54531a(7) =944035a(8) =18934763a(9) =431773963a(10) =11030464423a(11) =312023972228

External references