Expansion of 1 / (1 - Sum_{i>=1} Sum_{j=1..i} x^(i*j)).

Terms

a(0) =1a(1) =1a(2) =2a(3) =4a(4) =9a(5) =18a(6) =38a(7) =78a(8) =163a(9) =338a(10) =703a(11) =1458a(12) =3031a(13) =6293a(14) =13073a(15) =27150a(16) =56396a(17) =117130a(18) =243289a(19) =505310a(20) =1049552a(21) =2179938a(22) =4527804a(23) =9404355a(24) =19533126a(25) =40570816a(26) =84266725a(27) =175024267a(28) =363530253a(29) =755062265