a(n) = Sum_{j=1..n} Sum_{k=1..n} gcd(j*k,n).

Terms

a(0) =1a(1) =7a(2) =19a(3) =44a(4) =61a(5) =133a(6) =127a(7) =256a(8) =297a(9) =427a(10) =331a(11) =836a(12) =469a(13) =889a(14) =1159a(15) =1408a(16) =817a(17) =2079a(18) =1027a(19) =2684a(20) =2413a(21) =2317a(22) =1519a(23) =4864a(24) =2825a(25) =3283a(26) =4131a(27) =5588a(28) =2437a(29) =8113