Expansion of Sum_{n>=1} q^(n*(n-1)) / (1-q)^n.

Terms

a(0) =1a(1) =1a(2) =2a(3) =3a(4) =4a(5) =5a(6) =7a(7) =10a(8) =14a(9) =19a(10) =25a(11) =32a(12) =41a(13) =53a(14) =69a(15) =90a(16) =117a(17) =151a(18) =193a(19) =244a(20) =306a(21) =382a(22) =476a(23) =593a(24) =739a(25) =921a(26) =1147a(27) =1426a(28) =1768a(29) =2184