a(n) = (4*n+1)*(4*n+5).

Terms

a(0) =5a(1) =45a(2) =117a(3) =221a(4) =357a(5) =525a(6) =725a(7) =957a(8) =1221a(9) =1517a(10) =1845a(11) =2205a(12) =2597a(13) =3021a(14) =3477a(15) =3965a(16) =4485a(17) =5037a(18) =5621a(19) =6237a(20) =6885a(21) =7565a(22) =8277a(23) =9021a(24) =9797a(25) =10605a(26) =11445a(27) =12317a(28) =13221a(29) =14157