The "amusical permutation" of the nonnegative numbers: a(2n)=3n, a(4n+1)=3n+1, a(4n-1)=3n-1.

Terms

a(0) =0a(1) =1a(2) =3a(3) =2a(4) =6a(5) =4a(6) =9a(7) =5a(8) =12a(9) =7a(10) =15a(11) =8a(12) =18a(13) =10a(14) =21a(15) =11a(16) =24a(17) =13a(18) =27a(19) =14a(20) =30a(21) =16a(22) =33a(23) =17a(24) =36a(25) =19a(26) =39a(27) =20a(28) =42a(29) =22