[seqfan] More palindromes

[Eric Angelini]

Hello SeqFans,

S=1,10,11,12,13,14,15,16,17,18,19,91,9,29,20,21,22,23,24,25,26,27,28,82,8,38,30,...

Start with a(1)=1 and extend S with the smallest unused integer
such that a(n) concatenated to the leftmost digit of a(n+1), or
to the 2-leftmost digits of a(n+1), or to the 3-leftmost digits
of a(n+1), or... shows a palindrome.

Example:
1 and 10 show "11"
10 and 11 show "101"
11 and 12 show "111"
12 and 13 show "121"
...
19 and 91 show "1991" (100 would show "191" but 91 is smaller)
91 and 9 show "919", etc.

Best,
É.