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 A341055 #12 Apr 25 2021 15:12:40
%S A341055 0,1,4,2,3,12,13,11,5,6,7,10,8,9,36,37,35,38,39,40,34,32,33,15,16,14,
%T A341055 17,18,19,22,20,21,30,31,29,23,24,25,28,26,27,108,109,107,110,111,112,
%U A341055 106,104,105,114,115,113,116,117,118,121,119,120,102,103,101
%N A341055 Inverse permutation to A341054.
%C A341055 This sequence is similar to A003188.
%H A341055 Rémy Sigrist, <a href="/A341055/b341055.txt">Table of n, a(n) for n = 0..9841</a>
%H A341055 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a>
%e A341055 A341054(42) = 76, so a(76) = 42.
%o A341055 (PARI) a(n) = { my (d=[], s=Mod(0, 3)); while (n, my (t=centerlift(Mod(n, 3))); n=(n-t)\3; d=concat(t, d)); for (k=1, #d, d[k] = centerlift(d[k]-s); s+=d[k]); fromdigits(d, 3) }
%Y A341055 Cf. A003188, A059095, A341054.
%K A341055 nonn,base
%O A341055 0,3
%A A341055 _Rémy Sigrist_, Apr 25 2021