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.

1, 11, 9, 121, 11111, 13, 21613201, 1111, 333, 4961, 219660193449998401, 49, 17530969, 562529, 333, 2057, 79066065031254967758669825213076144489, 91

Offset: 1

Author

Jason Earls, Aug 13 2006

Keywords

• nonn

Comments

Sequence continues: r(19)^18, 18491, 1933, 2101917, r(23)^22, 143, 458002801, 161051, 50653, 34001, ... - Charlie Neder, Mar 06 2019

Examples

			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.
		

Links

• Charlie Neder, Table of n, a(n) for n = 1..37

Crossrefs

Cf. A121067.

Extensions

a(12)-a(18) from Charlie Neder, Mar 06 2019