%I #11 Jan 23 2018 04:47:24
%S 0,1,2,3,0,1,2,3,0,1,10,11,12,13,10,11,12,13,10,11,20,21,22,23,20,21,
%T 22,23,20,21,30,31,32,33,30,31,32,33,30,31,0,1,2,3,0,1,2,3,0,1,10,11,
%U 12,13,10,11,12,13,10,11,20,21,22,23,20,21,22,23,20,21,30,31,32,33,30,31,32
%N a(n) = n with each digit d of n replaced by d mod 4.
%H Vincenzo Librandi, <a href="/A132387/b132387.txt">Table of n, a(n) for n = 0..5000</a>
%e a(n) == n (mod 4) for n=0..9; a(n)=n for n=10..13; a(14)=10, a(15)=11,
%e a(41)=a(81)=1, etc.
%t Table[FromDigits[Mod[IntegerDigits[n],4]],{n,0,80}] (* _Harvey P. Dale_, Aug 25 2014 *)
%K base,nonn
%O 0,3
%A _Zak Seidov_, Nov 20 2007