a(n) = (2*n+1)*(9*n+1).

Terms

a(0) =1a(1) =30a(2) =95a(3) =196a(4) =333a(5) =506a(6) =715a(7) =960a(8) =1241a(9) =1558a(10) =1911a(11) =2300a(12) =2725a(13) =3186a(14) =3683a(15) =4216a(16) =4785a(17) =5390a(18) =6031a(19) =6708a(20) =7421a(21) =8170a(22) =8955a(23) =9776a(24) =10633a(25) =11526a(26) =12455a(27) =13420a(28) =14421a(29) =15458