a(n) = Sum_{k=1..n} sigma_2( (n/gcd(k,n))^2 ).

Terms

a(0) =1a(1) =22a(2) =183a(3) =704a(4) =2605a(5) =4026a(6) =14707a(7) =22548a(8) =44469a(9) =57310a(10) =147631a(11) =128832a(12) =344773a(13) =323554a(14) =476715a(15) =721596a(16) =1340977a(17) =978318a(18) =2352295a(19) =1833920a(20) =2691381a(21) =3247882a(22) =6168163a(23) =4126284a(24) =8140625a(25) =7585006a(26) =10806147a(27) =10353728a(28) =19827445a(29) =10487730