a(n) = (4*n^3 + 30*n^2 + 50*n)/3 + 1.

Terms

a(0) =1a(1) =29a(2) =85a(3) =177a(4) =313a(5) =501a(6) =749a(7) =1065a(8) =1457a(9) =1933a(10) =2501a(11) =3169a(12) =3945a(13) =4837a(14) =5853a(15) =7001a(16) =8289a(17) =9725a(18) =11317a(19) =13073a(20) =15001a(21) =17109a(22) =19405a(23) =21897a(24) =24593a(25) =27501a(26) =30629a(27) =33985a(28) =37577a(29) =41413