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

Terms

a(0) =1a(1) =15a(2) =77a(3) =247a(4) =609a(5) =1271a(6) =2365a(7) =4047a(8) =6497a(9) =9919a(10) =14541a(11) =20615a(12) =28417a(13) =38247a(14) =50429a(15) =65311a(16) =83265a(17) =104687a(18) =129997a(19) =159639a(20) =194081a(21) =233815a(22) =279357a(23) =331247a(24) =390049a(25) =456351a(26) =530765a(27) =613927a(28) =706497a(29) =809159