OFFSET
1,1
COMMENTS
All terms are odd since for even k, 2^k - 19 is divisible by 3.
a(26) > 5*10^5. - Tyler NeSmith, Apr 16 2022
LINKS
Henri Lifchitz and Renaud Lifchitz, Search for 2^n-19, PRP Top Records.
EXAMPLE
2^7 - 19 = 128 - 19 = 109, a prime, so 7 is a term of the sequence.
MATHEMATICA
Select[Range[5, 20000], PrimeQ[2^#-19]&] (* Vladimir Joseph Stephan Orlovsky, Feb 27 2011*)
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Labos Elemer, Jul 13 2004
EXTENSIONS
a(22)-a(23) from Max Alekseyev, Feb 10 2012
a(24)-a(25) from Lelio R Paula, added by Max Alekseyev, Oct 24 2013
a(26)-a(29) found by Stefano Morozzi, added by Alois P. Heinz, Aug 29 2022
STATUS
approved