a(n) = n^8 + n^6 + n^4 + n^2 + 1.

Terms

a(0) =1a(1) =5a(2) =341a(3) =7381a(4) =69905a(5) =406901a(6) =1727605a(7) =5884901a(8) =17043521a(9) =43584805a(10) =101010101a(11) =216145205a(12) =432988561a(13) =820586261a(14) =1483357205a(15) =2574332101a(16) =4311810305a(17) =6999978821a(18) =11054078101a(19) =17030739605a(20) =25664160401a(21) =37908820405a(22) =54989488181a(23) =78459301541a(24) =110266749505a(25) =152832422501