a(n) = A113572(n)/n.

Terms

a(0) =1a(1) =6a(2) =41a(3) =306a(4) =2449a(5) =20404a(6) =174895a(7) =1530303a(8) =13602694a(9) =0a(10) =1112947677a(11) =10202020369a(12) =94172495711a(13) =874458888747a(14) =0a(19) =0a(24) =0