a(n) = 1680*n^4 - 168*n^2 + 128*n + 1.

Terms

a(0) =1a(1) =1641a(2) =26465a(3) =134953a(4) =427905a(5) =1046441a(6) =2172001a(7) =4026345a(8) =6871553a(9) =11010025a(10) =16784481a(11) =24577961a(12) =34813825a(13) =47955753a(14) =64507745a(15) =85014121a(16) =110059521a(17) =140268905a(18) =176307553a(19) =218881065a(20) =268735361a(21) =326656681a(22) =393471585a(23) =470046953a(24) =557289985a(25) =656148201a(26) =767609441