This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A256308 #6 Mar 29 2015 14:34:57
%S A256308 1,2,3,4,5,6,7,0,21,22,23,24,25,26,27,20,31,32,33,34,35,36,37,30,41,
%T A256308 42,43,44,45,46,47,40,51,52,53,54,55,56,57,50,61,62,63,64,65,66,67,60,
%U A256308 71,72,73,74,75,76,77,70,1,2,3,4
%N A256308 Apply the transformation 0 -> 1 -> 2 -> 3 -> 4 -> 5 -> 6 -> 7 -> 0 to the digits of n written in base 8; do not convert back to base 10.
%C A256308 Base 8 variant of A256078 (base 2) and A048379 (base 10). See A256303 - A256307 for bases 3 through 7, A256289 for base 9, and A256298 for the variant where the result is converted back to base 10.
%e A256308 a(8) = 21 because 8 = "10" in base 8 becomes "21".
%e A256308 a(63) = 0 because 63 = "77" in base 8 becomes "00".
%t A256308 Table[FromDigits[IntegerDigits[n,8]/.{0->1,1->2,2->3,3->4,4->5,5->6,6->7,7->0}],{n,0,60}] (* _Harvey P. Dale_, Mar 29 2015 *)
%o A256308 (PARI) A256308(n,b=8)=!n+eval(Strchr(apply(d->(d+1)%b+48, digits(n,b))))
%K A256308 nonn,base,easy
%O A256308 0,2
%A A256308 _M. F. Hasler_, Mar 22 2015
%E A256308 Examples corrected by _Harvey P. Dale_, Mar 29 2015