a(n) = |{m : multiplicative order of 9 mod m = n}|.

Terms

a(0) =4a(1) =6a(2) =12a(3) =14a(4) =20a(5) =58a(6) =12a(7) =88a(8) =112a(9) =150a(10) =60a(11) =290a(12) =12a(13) =138a(14) =732a(15) =144a(16) =124a(17) =1088a(18) =60a(19) =670a(20) =740a(21) =570a(22) =28a(23) =13864a(24) =360a(25) =138a(26) =3968a(27) =1362a(28) =252a(29) =22058