a(n) = |{m : multiplicative order of 3 mod m = n}|.

Terms

a(0) =2a(1) =2a(2) =2a(3) =6a(4) =4a(5) =10a(6) =2a(7) =14a(8) =4a(9) =16a(10) =6a(11) =58a(12) =2a(13) =10a(14) =16a(15) =88a(16) =6a(17) =108a(18) =6a(19) =150a(20) =10a(21) =54a(22) =6a(23) =290a(24) =18a(25) =10a(26) =56a(27) =138a(28) =14a(29) =716