This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A307861 #39 May 08 2019 17:51:11
%S A307861 1,11,121,1111,12221,134431,1234321,1478741,1600951,17610461,
%T A307861 161696051,193715071,1634570971
%N A307861 Numbers that set records on longest chains of "Chained Divisors" of A306661 and A307858.
%C A307861 Here are the divisor chains:
%C A307861 Length---m----------Divisors
%C A307861 1 1 {1}
%C A307861 2 11 {1,11}
%C A307861 3 121 {1,11,121}
%C A307861 4 1111 {1,11,101,1111}
%C A307861 6 12221 {1,11,101,121,1111,12221}
%C A307861 8 134431 {1,11,101,121,1111,1331,12221,134431}
%C A307861 9 1234321 {1,11,101,121,1111,10201,12221,112211,1234321}
%C A307861 10 1478741 {1,11,101,121,1111,1331,12221,14641,134431,1478741}
%C A307861 The longest chain known is of number 1634570971 of length 24.
%C A307861 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
%o A307861 (PARI) { mx=0; for (n=1, oo, if (#(d=divisors(n))>mx, ok=1; d=apply(digits,d); for (i=1, #d-1, if (d[i][#d[i]]!=d[i+1][1], ok=0; break)); if (ok,
%o A307861 print1 (n ", "); mx=#d))) } \\ _Rémy Sigrist_, May 06 2019
%Y A307861 Cf. A307858, A306661.
%K A307861 nonn,base,more
%O A307861 1,2
%A A307861 _Giorgos Kalogeropoulos_, May 05 2019
%E A307861 a(11)-a(13) from _Rémy Sigrist_, May 06 2019