Generalized nim sum n + n in base 5.

Terms

a(0) =0a(1) =2a(2) =4a(3) =1a(4) =3a(5) =10a(6) =12a(7) =14a(8) =11a(9) =13a(10) =20a(11) =22a(12) =24a(13) =21a(14) =23a(15) =5a(16) =7a(17) =9a(18) =6a(19) =8a(20) =15a(21) =17a(22) =19a(23) =16a(24) =18a(25) =50a(26) =52a(27) =54a(28) =51a(29) =53