[seqfan] Divisors of the concatenation of n+1 and n

[Eric Angelini]

Hello SeqFans,
t(n) is the smallest unused integer so far in T such that t(n) is a divisor of the concatenation of n+1 and n.

     n =  1  2  3  4  5  6  7  8  9   10   11   12   13   14   15   16   17   18   19   20   21   22 
concat = 21 32 43 54 65 76 87 98 109 1110 1211 1312 1413 1514 1615 1716 1817 1918 2019 2120 2221 2322 
     T =  1, 2 43, 3, 5, 4,29, 7,109,  6,  173,  8,   9,  757, 17,  11,  23,  14,  673, 10, 2221, 18,...

Example:
The divisors of 1413 (concatenation of 14 and 13) are 1, 3, 9, 157, 471 and 1413. As 1 and 3 appear already in T, we have t(13) = 9.

Is T a permutation of the integers > 0 ?

Best,
É.