A339317 - OEIS

%I #21 Dec 13 2020 16:28:24

%S 1,3,10,4,5,6,7,8,30,11,12,15,17,19,21,13,2,22,28,9,31,14,35,37,39,41,

%T 16,45,47,49,51,18,55,52,26,61,20,65,56,62,27,73,25,57,74,42,29,85,58,

%U 86,66,69,95,67,79,96,70,105,68,89,101,23,32,59,102,60,107,80,114,46,91,24,48,90,123,36,92,64,50

%N Lexicographically earliest sequence of distinct positive terms such that a(n) is preceded by the a(n)-th digit of the sequence, for n > 1.

%C This sequence is a permutation of the numbers > 0.

%H Carole Dubois, <a href="/A339317/b339317.txt">Table of n, a(n) for n = 1..5001</a>

%e a(1) = 1

%e a(2) = 3 is preceded by the 3rd digit of the sequence (this is the 1 of 10);

%e a(3) = 10 is preceded by the 10th digit of the sequence (this is the 3 of 30);

%e a(4) = 4 is preceded by the 4th digit of the sequence (this is the 0 of 10);

%e a(5) = 5 is preceded by the 5th digit of the sequence (this is the 4 of 4);

%e ...

%e a(9) = 30 because this is the smallest integer not leading to a contradiction [it must start with a 3 because of a(3) fixing the 10th digit of the sequence];  etc.

%Y Cf. A339206 (a variant of this sequence).

%K base,nonn

%O 1,2

%A _Eric Angelini_ and _Carole Dubois_, Nov 30 2020