a(n) = (n+3)^2*n/2 + 1.

Terms

a(0) =1a(1) =9a(2) =26a(3) =55a(4) =99a(5) =161a(6) =244a(7) =351a(8) =485a(9) =649a(10) =846a(11) =1079a(12) =1351a(13) =1665a(14) =2024a(15) =2431a(16) =2889a(17) =3401a(18) =3970a(19) =4599a(20) =5291a(21) =6049a(22) =6876a(23) =7775a(24) =8749a(25) =9801a(26) =10934a(27) =12151a(28) =13455a(29) =14849