cp's OEIS Frontend

A303446 Lexicographically first sequence of distinct terms such that a(n) can be recreated concatenating [the last digit(s) of a(n-1)] to [the first digit(s) of a(n+1)].

%I A303446 #8 Dec 01 2019 23:14:09
%S A303446 1,11,12,21,13,31,14,41,15,51,16,61,17,71,18,81,19,91,110,101,111,112,
%T A303446 22,23,32,24,42,25,52,26,62,27,72,28,82,29,92,210,102,211,113,33,34,
%U A303446 43,35,53,36,63,37,73,38,83,39,93,310,103,311,114,44,45,54,46,64,47,74,48,84,49,94,410,104,411
%N A303446 Lexicographically first sequence of distinct terms such that a(n) can be recreated concatenating [the last digit(s) of a(n-1)] to [the first digit(s) of a(n+1)].
%C A303446 The sequence is started with a(1) = 1 and always extended with the smallest term not present that doesn't lead to a contradiction.
%H A303446 Jean-Marc Falcoz, <a href="/A303446/b303446.txt">Table of n, a(n) for n = 1..4003</a>
%e A303446 a(2) = 11  is [1] concatenated to [the first 1 of 12];
%e A303446 a(3) = 12  is [the last 1 of 11] concatenated to [the 2 of 21];
%e A303446 a(4) = 21  is [the 2 of 12] concatenated to [the 1 of 13];
%e A303446 a(5) = 13  is [the 1 of 21] concatenated to [the 3 of 31];
%e A303446 a(6) = 31  is [the 3 of 13] concatenated to [the 1 of 14];
%e A303446 a(7) = 14  is [the 1 of 31] concatenated to [the 4 of 41];
%e A303446 etc.
%K A303446 nonn,base
%O A303446 1,2
%A A303446 _Jean-Marc Falcoz_ and _Eric Angelini_, Apr 24 2018