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Numbers k such that k*8^k + 1 is prime.
4

%I #18 Sep 08 2022 08:46:08

%S 5,17,23,1911,20855,35945,42816

%N Numbers k such that k*8^k + 1 is prime.

%H G. Loeh, <a href="http://guenter.loeh.name/gc/status.html">Generalized Cullen primes</a>

%t Select[Range[2000], PrimeQ[# 8^# + 1] &]

%o (Magma) [n: n in [0..2000] | IsPrime(n*8^n+1)];

%o (PARI) is(n)=ispseudoprime(n*8^n+1) \\ _Charles R Greathouse IV_, May 22 2017

%Y Cf. similar sequences listed in A242176.

%K nonn,more

%O 1,1

%A _Vincenzo Librandi_, May 08 2014

%E a(5)-a(7) from Loeh's list (see Links) - _Bruno Berselli_, May 08 2014