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

Terms

a(0) =2a(1) =11a(2) =30a(3) =62a(4) =110a(5) =177a(6) =266a(7) =380a(8) =522a(9) =695a(10) =902a(11) =1146a(12) =1430a(13) =1757a(14) =2130a(15) =2552a(16) =3026a(17) =3555a(18) =4142a(19) =4790a(20) =5502a(21) =6281a(22) =7130a(23) =8052a(24) =9050a(25) =10127a(26) =11286a(27) =12530a(28) =13862a(29) =15285