a(n) = sigma_4(n^2)/sigma_2(n^2).

Terms

a(0) =1a(1) =13a(2) =73a(3) =205a(4) =601a(5) =949a(6) =2353a(7) =3277a(8) =5905a(9) =7813a(10) =14521a(11) =14965a(12) =28393a(13) =30589a(14) =43873a(15) =52429a(16) =83233a(17) =76765a(18) =129961a(19) =123205a(20) =171769a(21) =188773a(22) =279313a(23) =239221a(24) =375601a(25) =369109a(26) =478297a(27) =482365a(28) =706441a(29) =570349