%I #16 Oct 15 2016 09:46:51
%S 1,2,14,22,1582,11266,52766,76202,100562,494371,641141,1698494,
%T 66593158,469296521,10917186079,12062558662,4928050067287,
%U 5315948729617,29841213777637,113215787397262,778590786358582,787324867879046
%N Numbers n such that 13^n == 15 (mod n).
%C No other terms below 10^15. Some large terms: 6991413003775539262, 2360895769139218729155198091. - _Max Alekseyev_, Oct 15 2016
%t Select[Range[25000000],PowerMod[13,#,# ]==15&] (* _Harvey P. Dale_, Feb 03 2009 *)
%Y Cf. A116609, A116611, A116620, A116621, A116622, A116629, A116630, A116631, A116632, A116636, A116638.
%K nonn
%O 1,2
%A _Zak Seidov_, Feb 19 2006
%E One more term from _Harvey P. Dale_, Feb 03 2009
%E Edited by _Max Alekseyev_, Sep 19 2009
%E a(14)-a(22) from _Max Alekseyev_, May 04 2010, Apr 29 2014, Oct 15 2016