a(n) = [x^n] Product_{k=1..2*n} 1/(1 - k * x).

A348084

a(n) = [x^n] Product_{k=1..2*n} 1/(1 - k * x).

Terms

    a(0) =1a(1) =3a(2) =65a(3) =2646a(4) =159027a(5) =12662650a(6) =1256328866a(7) =149304004500

External references