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Numbers n such that 111*10^n+1 is prime.
1

%I #9 Dec 15 2017 17:36:44

%S 8,16,20,62,64,76,100,142,230,670,2230,167644

%N Numbers n such that 111*10^n+1 is prime.

%C a(1) through a(11) have been proved to be prime with WinPFGW.

%o (PARI) is(n)=ispseudoprime(111*10^n+1) \\ _Charles R Greathouse IV_, Jun 12 2017

%K more,nonn

%O 1,1

%A _Jason Earls_, Aug 17 2004

%E a(12) from _Predrag Kurtovic_, May 24 2015