a(n) = 2*n^4/3 - 4*n^3/3 + 11*n^2/6 - 13*n/6 + 1.

Terms

a(0) =1a(1) =0a(2) =4a(3) =29a(4) =107a(5) =286a(6) =630a(7) =1219a(8) =2149a(9) =3532a(10) =5496a(11) =8185a(12) =11759a(13) =16394a(14) =22282a(15) =29631a(16) =38665a(17) =49624a(18) =62764a(19) =78357a(20) =96691a(21) =118070a(22) =142814a(23) =171259a(24) =203757a(25) =240676a(26) =282400a(27) =329329a(28) =381879a(29) =440482