a(n) = 1 + n^4 + n^6 + n^9.

Terms

a(0) =4a(1) =593a(2) =20494a(3) =266497a(4) =1969376a(5) =10125649a(6) =40473658a(7) =134483969a(8) =387958492a(9) =1001010001a(10) =2359733894a(11) =5162787073a(12) =10609354744a(13) =20668614737a(14) =38454800626a(15) =68736319489a(16) =118612097588a(17) =198393407569a(18) =322734873982a(19) =512064160001