a(n) = floor(exp(20/23) * n!).

Terms

a(0) =2a(1) =4a(2) =14a(3) =57a(4) =286a(5) =1717a(6) =12024a(7) =96198a(8) =865785a(9) =8657857a(10) =95236427a(11) =1142837124a(12) =14856882614a(13) =207996356596