OFFSET
1,1
COMMENTS
a(14) > 5*10^5. - Robert Price, Aug 27 2015
All terms are even. - Robert Israel, Aug 28 2015
For numbers k in this sequence, the number 2^(k-1)*(2^k+19) has deficiency 20 (see A223607). - M. F. Hasler, Jul 18 2016
LINKS
Henri Lifchitz and Renaud Lifchitz (Editors), Search for 2^n+19, PRP Top Records.
FORMULA
a(n) = 2*A253774(n). - Joerg Arndt, Aug 28 2015
MAPLE
select(n -> isprime(2^n+19), [seq(2*i, i=1..10000)]); # Robert Israel, Aug 28 2015
MATHEMATICA
Do[ If[ PrimeQ[ 2^n + 19 ], Print[ n ] ], {n, 1, 15000} ]
Select[Range[10000], PrimeQ[2^# + 19] &] (* Vincenzo Librandi, Aug 28 2015 *)
PROG
(Magma) [n: n in [0..1000] | IsPrime(2^n+19)]; // Vincenzo Librandi, Aug 28 2015
(PARI) for(n=1, 9e9, ispseudoprime(2^n+19)&&print1(n", ")) \\ M. F. Hasler, Jul 18 2016
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Robert G. Wilson v, Sep 17 2000
EXTENSIONS
a(11)-a(13) from Robert Price, Aug 27 2015
Edited by M. F. Hasler, Jul 18 2016
a(14)-a(15) found by Stefano Morozzi, added by Elmo R. Oliveira, Nov 19 2023
STATUS
approved