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

Terms

a(0) =1a(1) =-3a(2) =6a(3) =-21a(4) =69a(5) =-201a(6) =591a(7) =-1785a(8) =5406a(9) =-16194a(10) =48426a(11) =-145380a(12) =436641a(13) =-1309611a(14) =3927399a(15) =-11783280a(16) =35354139a(17) =-106059387a(18) =318165729a(19) =-954506190a(20) =2863556475a(21) =-8590643832a(22) =25771817454a(23) =-77315531169a(24) =231946940175a(25) =-695840583126