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%I #46 Sep 08 2022 08:46:08
%S 0,1,3,21,145,273,1425,9613,15711,18445
%N Numbers n such that 19^n+4 is prime.
%C No further terms up to 20000. - _Felix Fröhlich_, Oct 29 2014
%C No further terms up to 24000. - _Felix Fröhlich_, Jan 22 2015
%t Select[Range[0, 10000], PrimeQ[19^# + 4] &] (* _Vincenzo Librandi_, Oct 16 2014 *)
%o (PARI) for(n=0, 10^5, if(ispseudoprime(19^n+4), print1(n, ", ")))
%o (Magma) [n: n in [0..1000] | IsPrime(19^n+4)]; // _Vincenzo Librandi_, Oct 16 2014
%Y Corresponding sequences for k^n+4: A058958 (k=3), A124621 (k=5), A096305 (k=7), A217384 (k=9), A137236 (k=13).
%K nonn,more
%O 1,3
%A _Felix Fröhlich_, Jun 04 2014
%E a(1)-a(2) prepended by _N. J. A. Sloane_, Jun 18 2014
%E a(9)-a(10) from _Felix Fröhlich_, Oct 16 2014
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