Expansion of 1/2 * Product_{i>=0, j>=0, k>=0} (1 + x^(i^2 + j^2 + k^2)).

Terms

a(0) =1a(1) =3a(2) =6a(3) =11a(4) =18a(5) =33a(6) =59a(7) =96a(8) =150a(9) =230a(10) =357a(11) =552a(12) =825a(13) =1203a(14) =1749a(15) =2541a(16) =3666a(17) =5208a(18) =7302a(19) =10212a(20) =14250a(21) =19738a(22) =27093a(23) =36936a(24) =50203a(25) =68034a(26) =91665a(27) =122763a(28) =163731a(29) =217740