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

Terms

a(0) =1a(1) =6a(2) =24a(3) =96a(4) =330a(5) =1104a(6) =3552a(7) =11184a(8) =34584a(9) =105990a(10) =322224a(11) =975264a(12) =2942016a(13) =8857680a(14) =26631312a(15) =80005632a(16) =240219114a(17) =721036320a(18) =2163789816a(19) =6492625152a(20) =19480105392a(21) =58444390176a(22) =175340344416a(23) =526034008752