a(n) = numerator(b(n)), where b(1) = b(2) = 1, b(n) = (b(n-1) + b(n-2))/(n-1).

Terms

a(0) =1a(1) =1a(2) =1a(3) =2a(4) =5a(5) =13a(6) =19a(7) =29a(8) =191a(9) =131a(10) =1187a(11) =2231a(12) =17519a(13) =71063a(14) =29881a(15) =323423a(16) =2887921a(17) =13237457a(18) =2397389a(19) =15030317a(20) =742458253a(21) =3748521653a(22) =9670072483a(23) =25451905333a(24) =10932619111a(25) =78684575461