A109492 - OEIS

%I #22 Sep 27 2023 12:14:36

%S 1,3,7,11,13,21,33,37,39,77,91,111,143,231,259,273,407,429,481,777,

%T 1001,1221,1443,2849,3003,3367,5291,8547,10101,15873,37037,111111

%N Divisors of 111111.

%C Note that the smaller repunits R3=111, R4=1111, R5=11111 are semiprimes and have only 4 divisors, which is again the case for the next repunit R7=1111111. - _M. F. Hasler_, Oct 13 2011

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/Repunit.html">Repunit</a>

%H <a href="/index/Di#divisors">Index entries for sequences related to divisors of numbers</a>

%t Divisors[111111] (* _Paolo Xausa_, Sep 27 2023 *)

%o (PARI) divisors(111111) \\ _Michel Marcus_, Sep 08 2015

%Y Cf. A070529, A018282, A018766, A027894, A027893, A027892, A027891, A027890, A027889, A027895. [_M. F. Hasler_, Oct 13 2011]

%Y Cf. A199799 (totatives of 111111), A154549 (111111*n).

%K nonn,fini,full,easy

%O 1,2

%A _Philippe Deléham_, Aug 28 2005