For n >= 1, a(n) = A159666(n)/n.

Terms

a(0) =1a(1) =2a(2) =6a(3) =26a(4) =133a(5) =905a(6) =6521a(7) =57126a(8) =544820a(9) =5878219a(10) =66851119a(11) =881424550a(12) =11803494823a(13) =175906313032