%I #13 Sep 08 2022 08:46:08
%S 13992265,1504651681,14782305601,292869912385,2387706608354185,
%T 4484354372982001,70895950685971489,807481759780458361,
%U 1659264916949696161,118023300545190612481,140695625117781970705,11710597360056333492601,19818019625768288167321
%N Carmichael numbers of the form (6*k + 1)*(12*k + 1)*(18*k + 1), where only one of the three numbers 6*k + 1, 12*k + 1, 18*k + 1 is prime.
%H Giovanni Resta, <a href="/A242981/b242981.txt">Table of n, a(n) for n = 1..26</a> (terms < 4*10^33)
%H Carlos Rivera, <a href="http://www.primepuzzles.net/puzzles/puzz_739.htm">Puzzle 739</a>
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/CarmichaelNumber.html">Carmichael Number</a>
%H <a href="/index/Ca#Carmichael">Index entries for sequences related to Carmichael numbers</a>
%o (Magma) lst:=[]; for k in [1..2482095] do t:={n: n in [1..3] | IsPrime(6*k*n+1)}; if #Set(t) eq 1 then c:=&*[6*k*n+1: n in [1..3]]; if IsOne(c mod CarmichaelLambda(c)) then lst:=Append(lst, c); end if; end if; end for; lst;
%Y Cf. A002997, A033502, A242980.
%K nonn
%O 1,1
%A _Arkadiusz Wesolowski_, May 28 2014