a(n) = |{m : multiplicative order of 4 mod m=n}|.

Terms

a(0) =2a(1) =2a(2) =4a(3) =4a(4) =6a(5) =16a(6) =6a(7) =8a(8) =26a(9) =38a(10) =14a(11) =68a(12) =6a(13) =54a(14) =84a(15) =16a(16) =6a(17) =462a(18) =6a(19) =140a(20) =132a(21) =110a(22) =14a(23) =664a(24) =120a(25) =118a(26) =128a(27) =188a(28) =62a(29) =4456