a(n) = 1 + sigma(n) + sigma(n)^2 + sigma(n)^3 + sigma(n)^4.

Terms

a(0) =5a(1) =121a(2) =341a(3) =2801a(4) =1555a(5) =22621a(6) =4681a(7) =54241a(8) =30941a(9) =111151a(10) =22621a(11) =637421a(12) =41371a(13) =346201a(14) =346201a(15) =954305a(16) =111151a(17) =2374321a(18) =168421a(19) =3187591a(20) =1082401a(21) =1727605a(22) =346201a(23) =13179661a(24) =954305a(25) =3187591a(26) =2625641a(27) =10013305a(28) =837931a(29) =27252361