a(n) = (n+1)*(6*n^4 - 51*n^3 + 161*n^2 - 251*n + 251).

Terms

a(0) =251a(1) =232a(2) =243a(3) =224a(4) =475a(5) =2376a(6) =9107a(7) =26368a(8) =63099a(9) =132200a(10) =251251a(11) =443232a(12) =737243a(13) =1169224a(14) =1782675a(15) =2629376a(16) =3770107a(17) =5275368a(18) =7226099a(19) =9714400a(20) =12844251a(21) =16732232a(22) =21508243a(23) =27316224a(24) =34314875a(25) =42678376a(26) =52597107a(27) =64278368a(28) =77947099