Constant term in the expansion of (1 + x^4 + y^4 + 1/(x*y))^n.

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =1a(5) =1a(6) =31a(7) =211a(8) =841a(9) =2521a(10) =6301a(11) =13861a(12) =30691a(13) =90091a(14) =360361a(15) =1501501a(16) =5645641a(17) =18749641a(18) =56063281a(19) =157520641a(20) =445836901a(21) =1368402421a(22) =4638690211a(23) =16511900791a(24) =58059667051a(25) =195211574251a(26) =625463703151