a(n) = 12*n^2 + 2*n + 1.

Terms

a(0) =1a(1) =15a(2) =53a(3) =115a(4) =201a(5) =311a(6) =445a(7) =603a(8) =785a(9) =991a(10) =1221a(11) =1475a(12) =1753a(13) =2055a(14) =2381a(15) =2731a(16) =3105a(17) =3503a(18) =3925a(19) =4371a(20) =4841a(21) =5335a(22) =5853a(23) =6395a(24) =6961a(25) =7551a(26) =8165a(27) =8803a(28) =9465a(29) =10151