a(n) = (2*n+1)*(10*n+1).

Terms

a(0) =1a(1) =33a(2) =105a(3) =217a(4) =369a(5) =561a(6) =793a(7) =1065a(8) =1377a(9) =1729a(10) =2121a(11) =2553a(12) =3025a(13) =3537a(14) =4089a(15) =4681a(16) =5313a(17) =5985a(18) =6697a(19) =7449a(20) =8241a(21) =9073a(22) =9945a(23) =10857a(24) =11809a(25) =12801a(26) =13833a(27) =14905a(28) =16017a(29) =17169