a(n) = sigma(n) * binomial(2*n-1,n), for n >= 1.

Terms

a(0) =1a(1) =9a(2) =40a(3) =245a(4) =756a(5) =5544a(6) =13728a(7) =96525a(8) =316030a(9) =1662804a(10) =4232592a(11) =37858184a(12) =72804200a(13) =481399200a(14) =1861410240a(15) =9316746045a(16) =21002455980a(17) =176965138350a(18) =353452638000