OFFSET
1,2
COMMENTS
The sequence starts with a(1) = 1 and is always extended with the smallest integer not yet present that doesn't lead to a contradiction.
LINKS
Jean-Marc Falcoz, Table of n, a(n) for n = 1..302 (shortened by N. J. A. Sloane, Jan 18 2019)
EXAMPLE
The first nine terms are replaced by themselves;
11 = a(10) is replaced by the product 1 * 1 = 1;
26 = a(11) is replaced by the product 2 * 6 = 12;
16 = a(12) is replaced by the product 1 * 6 = 6;
28 = a(13) is replaced by the product 2 * 8 = 16;
12 = a(14) is replaced by the product 1 * 2 = 2;
18 = a(15) is replaced by the product 1 * 8 = 8;
34 = a(16) is replaced by the product 3 * 4 = 12;
29 = a(17) is replaced by the product 2 * 9 = 18;
13 = a(18) is replaced by the product 1 * 3 = 3;
14 = a(19) is replaced by the product 1 * 4 = 4;
etc.
We see that the first and the last column here (the terms of S and S') share the same succession of digits: 1,1,2,6,1,6,2,8,1,2,1,8,3,4,...
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Eric Angelini and Jean-Marc Falcoz, Apr 17 2018
STATUS
approved