a(n) = (1/n) * Sum_{k=1..n} tau( (n/gcd(k,n))^n ).

Terms

a(0) =1a(1) =2a(2) =3a(3) =6a(4) =5a(5) =20a(6) =7a(7) =18a(8) =15a(9) =54a(10) =11a(11) =144a(12) =13a(13) =104a(14) =143a(15) =50a(16) =17a(17) =290a(18) =19a(19) =442a(20) =285a(21) =252a(22) =23a(23) =884a(24) =45a(25) =350a(26) =69a(27) =900a(28) =29a(29) =8400