a(n)=4n^4-3n^3+2n^2-n+1.

Terms

a(0) =1a(1) =3a(2) =47a(3) =259a(4) =861a(5) =2171a(6) =4603a(7) =8667a(8) =14969a(9) =24211a(10) =37191a(11) =54803a(12) =78037a(13) =107979a(14) =145811a(15) =192811a(16) =250353a(17) =319907a(18) =403039a(19) =501411a(20) =616781a(21) =751003a(22) =906027a(23) =1083899a(24) =1286761a(25) =1516851a(26) =1776503a(27) =2068147a(28) =2394309a(29) =2757611