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 A373712 #14 Aug 06 2024 16:38:45
%S A373712 0,1,1,3,4,3,3,3,4,9,10,11,12,13,12,11,10,9,9,11,10,11,9,10,12,12,13,
%T A373712 27,28,29,30,31,32,33,34,35,36,37,38,39,40,39,38,37,36,35,34,33,32,31,
%U A373712 30,29,28,27,27,29,28,33,35,34,30,32,31,35,33,34,29,27
%N A373712 a(n) is the least m >= 0 with the same number of ternary digits as n such that for some permutation p of 0..2, applying p to the ternary digits of n yields the ternary digits of m.
%C A373712 Leading zeros in ternary expansions are ignored.
%C A373712 Empirically, A134025 corresponds to the fixed points of this sequence.
%C A373712 The lexicographically latest sequence b of distinct nonnegative integers such that for any n >= 0, a(n) = a(b(n)) is A371268.
%H A373712 Rémy Sigrist, <a href="/A373712/b373712.txt">Table of n, a(n) for n = 0..6560</a>
%F A373712 a(n) <= n.
%F A373712 a(a(n)) = a(n).
%e A373712 The first terms, alongside their ternary expansions, are:
%e A373712 n a(n) ter(n) ter(a(n))
%e A373712 -- ---- ------ ---------
%e A373712 0 0 0 0
%e A373712 1 1 1 1
%e A373712 2 1 2 1
%e A373712 3 3 10 10
%e A373712 4 4 11 11
%e A373712 5 3 12 10
%e A373712 6 3 20 10
%e A373712 7 3 21 10
%e A373712 8 4 22 11
%e A373712 9 9 100 100
%e A373712 10 10 101 101
%e A373712 11 11 102 102
%e A373712 12 12 110 110
%e A373712 13 13 111 111
%e A373712 14 12 112 110
%e A373712 15 11 120 102
%e A373712 16 10 121 101
%o A373712 (PARI) a(n, base = 3) = { my (d = digits(n, base), m = vector(base, i, -1), u = 1); for (i = 1, #d, if (m[1+d[i]] < 0, m[1+d[i]] = u; u = if (u==1, 0, u==0, 2, u+1);); d[i] = m[1+d[i]];); fromdigits(d, base); }
%Y A373712 Cf. A134025, A371268, A373696 (decimal analog).
%K A373712 nonn,base
%O A373712 0,4
%A A373712 _Rémy Sigrist_, Aug 04 2024