a(n) = Sum_{k=1..n} gcd(k, n)^6.

Terms

a(0) =1a(1) =65a(2) =731a(3) =4162a(4) =15629a(5) =47515a(6) =117655a(7) =266372a(8) =532905a(9) =1015885a(10) =1771571a(11) =3042422a(12) =4826821a(13) =7647575a(14) =11424799a(15) =17047816a(16) =24137585a(17) =34638825a(18) =47045899a(19) =65047898a(20) =86005805a(21) =115152115a(22) =148035911a(23) =194717932a(24) =244203145a(25) =313743365a(26) =388487763a(27) =489680110a(28) =594823349