a(n) = Sum_{k=1..n, gcd(n,k) = 1} k^4.

Terms

a(0) =1a(1) =1a(2) =17a(3) =82a(4) =354a(5) =626a(6) =2275a(7) =3108a(8) =7395a(9) =9044a(10) =25333a(11) =17668a(12) =60710a(13) =50470a(14) =88388a(15) =103496a(16) =243848a(17) =129750a(18) =432345a(19) =266088a(20) =497574a(21) =497178a(22) =1151403a(23) =539912a(24) =1541770a(25) =1153724a(26) =1900089a(27) =1516844a(28) =3756718a(29) =1246568