Expansion of Product_{k>=0} 1/(1-x^(3*k+1))^4.

Terms

a(0) =1a(1) =4a(2) =10a(3) =20a(4) =39a(5) =72a(6) =124a(7) =204a(8) =331a(9) =524a(10) =806a(11) =1216a(12) =1813a(13) =2660a(14) =3846a(15) =5500a(16) =7790a(17) =10916a(18) =15158a(19) =20880a(20) =28544a(21) =38736a(22) =52226a(23) =69972a(24) =93200a(25) =123460a(26) =162700a(27) =213340a(28) =278459a(29) =361860