a(n) = (n^3)/2 + (3*n^2)/2 + 3*n + 3.

Terms

a(0) =8a(1) =19a(2) =39a(3) =71a(4) =118a(5) =183a(6) =269a(7) =379a(8) =516a(9) =683a(10) =883a(11) =1119a(12) =1394a(13) =1711a(14) =2073a(15) =2483a(16) =2944a(17) =3459a(18) =4031a(19) =4663a(20) =5358a(21) =6119a(22) =6949a(23) =7851a(24) =8828a(25) =9883a(26) =11019a(27) =12239a(28) =13546a(29) =14943