cp's OEIS Frontend

Here are the divisor chains:

Length---m----------Divisors

1 1 {1}

2 11 {1,11}

3 121 {1,11,121}

4 1111 {1,11,101,1111}

6 12221 {1,11,101,121,1111,12221}

8 134431 {1,11,101,121,1111,1331,12221,134431}

9 1234321 {1,11,101,121,1111,10201,12221,112211,1234321}

10 1478741 {1,11,101,121,1111,1331,12221,14641,134431,1478741}

The longest chain known is of number 1634570971 of length 24.

Under the assumption that all divisors begin and end with 1, the next terms are 19565222171, 153203879191, 165091668071, 197783087491, and 1685242671101, with 30, 32, 36, 40, and 48 divisors, respectively. - Charlie Neder, May 08 2019