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

A321968

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

Terms

    a(0) =-1a(1) =3a(2) =7a(3) =55a(4) =735a(5) =13851a(6) =336743a(7) =10024911a(8) =353109375a(9) =14361853555a(10) =662358958599

External references