a(n) = Sum_{1 <= j <= n/2, gcd(j,n)=1} j^4.

Terms

a(0) =0a(1) =1a(2) =1a(3) =1a(4) =17a(5) =1a(6) =98a(7) =82a(8) =273a(9) =82a(10) =979a(11) =626a(12) =2275a(13) =707a(14) =2674a(15) =3108a(16) =8772a(17) =3027a(18) =15333a(19) =9044a(20) =14994a(21) =9669a(22) =39974a(23) =17668a(24) =50085a(25) =24310a(26) =60597a(27) =50470a(28) =127687a(29) =45604