G.f.: exp( Sum_{n>=1} A020696(n) * x^n/n ), where A020696(n) = Product_{d|n} (d + 1).

Terms

a(0) =1a(1) =2a(2) =5a(3) =10a(4) =24a(5) =44a(6) =109a(7) =198a(8) =423a(9) =766a(10) =1555a(11) =2730a(12) =6269a(13) =11090a(14) =22127a(15) =39246a(16) =77541a(17) =134242a(18) =270348a(19) =467004a(20) =895797a(21) =1546922a(22) =2905899a(23) =4943126a(24) =9666435a(25) =16471506a(26) =30604583a(27) =52206218a(28) =96412319a(29) =162467222