A107280 - OEIS

%I #10 Sep 20 2024 11:53:24

%S 11,36,53,54,109,123,259,380,877,1205,1795,14153,21965

%N Numbers k such that 22446688 * 10^k + 1 is prime.

%C These are almost-all-even-digits primes and they have all been certified. No more terms up to 25000. Primality proof for the largest: PFGW Version 20041001.Win_Stable (v1.2 RC1b) [FFT v23.8] Primality testing 22446688*10^21965+1 [N-1, Brillhart-Lehmer-Selfridge] Running N-1 test using base 3 22446688*10^21965+1 is prime! (70.7023s+0.0215s)

%H R. Ondrejka, <a href="http://www.utm.edu/research/primes/lists/top_ten/">The Top Ten: a Catalogue of Primal Configurations</a>.

%o (PARI) is(n)=ispseudoprime(22446688*10^n+1) \\ _Charles R Greathouse IV_, Jun 13 2017

%Y Cf. A068690.

%K nonn

%O 1,1

%A _Jason Earls_, May 19 2005