G.f.: A(x) = Sum_{n>=0} x^n / Product_{k=1..n} (1 - k*x^k).

Terms

a(0) =1a(1) =1a(2) =2a(3) =3a(4) =6a(5) =9a(6) =19a(7) =29a(8) =57a(9) =94a(10) =172a(11) =280a(12) =519a(13) =833a(14) =1472a(15) =2433a(16) =4185a(17) =6800a(18) =11666a(19) =18816a(20) =31686a(21) =51340a(22) =84929a(23) =136561a(24) =225476a(25) =359746a(26) =586133a(27) =936243a(28) =1511650a(29) =2397400