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A121154 a(n) = the n-th divisor of r(n)^n, where r(n) = (10^n-1)/9 the repunits and the positive divisors of r(n)^n are written in order from smallest to largest.

%I A121154 #14 Mar 08 2019 03:55:05
%S A121154 1,11,9,121,11111,13,21613201,1111,333,4961,219660193449998401,49,
%T A121154 17530969,562529,333,2057,79066065031254967758669825213076144489,91
%N A121154 a(n) = the n-th divisor of r(n)^n, where r(n) = (10^n-1)/9 the repunits and the positive divisors of r(n)^n are written in order from smallest to largest.
%C A121154 Sequence continues: r(19)^18, 18491, 1933, 2101917, r(23)^22, 143, 458002801, 161051, 50653, 34001, ... - _Charlie Neder_, Mar 06 2019
%H A121154 Charlie Neder, <a href="/A121154/b121154.txt">Table of n, a(n) for n = 1..37</a>
%e A121154 1, 11, 101, 121, 1111, 1331, 10201, 12221, 14641, 112211, 134431,... is the beginning of the sequence of divisors of 1111^4 and 121 is the 4th term of this sequence, so a(4) = 121.
%Y A121154 Cf. A121067.
%K A121154 nonn
%O A121154 1,2
%A A121154 _Jason Earls_, Aug 13 2006
%E A121154 a(12)-a(18) from _Charlie Neder_, Mar 06 2019