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

Terms

a(0) =1a(1) =1a(2) =2a(3) =3a(4) =7a(5) =14a(6) =30a(7) =65a(8) =132a(9) =280a(10) =632a(11) =1439a(12) =3299a(13) =7569a(14) =17450a(15) =40313a(16) =92889a(17) =212801a(18) =483590a(19) =1092649a(20) =2467078a(21) =5581232a(22) =12690828a(23) =29123728a(24) =67648617a(25) =159370347a(26) =381080620a(27) =923803158a(28) =2264970530a(29) =5599185887