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 A106747 #15 Apr 08 2022 08:14:27 %S A106747 0,0,1,1,2,2,3,3,4,4,0,0,1,1,2,2,3,3,4,4,10,10,11,11,12,12,13,13,14, %T A106747 14,10,10,11,11,12,12,13,13,14,14,20,20,21,21,22,22,23,23,24,24,20,20, %U A106747 21,21,22,22,23,23,24,24,30,30,31,31,32,32,33,33,34,34,30,30,31,31,32,32 %N A106747 Replace each odd digit d of n with (d-1)/2 and each even digit d with d/2. %C A106747 Terms are repeated. Differs from A004526 and A021895 starting with a(11)=0, A004526(11)=A021895(11)=5. %H A106747 Reinhard Zumkeller, <a href="/A106747/b106747.txt">Table of n, a(n) for n = 0..10000</a> %t A106747 a[n_]:=FromDigits[Map[If[Mod[ #, 2]==1, (#-1)/2, #/2]&, IntegerDigits[n]]];Table[a[n], {n, 0, 100}] %o A106747 (Haskell) %o A106747 a106747 n = if n == 0 then 0 else 10 * (a106747 n') + div d 2 %o A106747 where (n', d) = divMod n 10 %o A106747 -- _Reinhard Zumkeller_, Jan 14 2015 %o A106747 (Python) %o A106747 def A106747(n): return int(str(n).translate({49:48,50:49,51:49,52:50,53:50,54:51,55:51,56:52,57:52})) # _Chai Wah Wu_, Apr 07 2022 %Y A106747 Cf. A004526, A021895, A107128, A107130. %K A106747 nonn,base,look %O A106747 0,5 %A A106747 _Zak Seidov_, May 12 2005