a(n) = 2^n * n! * [x^n] (-1/2 - exp(-x))^n.

A375541

a(n) = 2^n * n! * [x^n] (-1/2 - exp(-x))^n.

Terms

    a(0) =1a(1) =2a(2) =20a(3) =318a(4) =7080a(5) =202650a(6) =7089516a(7) =293122998a(8) =13984363728a(9) =756140833458

External references