a(n) = (2*n+1)*(11*n+1).

Terms

a(0) =1a(1) =36a(2) =115a(3) =238a(4) =405a(5) =616a(6) =871a(7) =1170a(8) =1513a(9) =1900a(10) =2331a(11) =2806a(12) =3325a(13) =3888a(14) =4495a(15) =5146a(16) =5841a(17) =6580a(18) =7363a(19) =8190a(20) =9061a(21) =9976a(22) =10935a(23) =11938a(24) =12985a(25) =14076a(26) =15211a(27) =16390a(28) =17613a(29) =18880