OFFSET
1,1
COMMENTS
a(4) > prime(10^8)=2038074743.
Number 2*10^k-1 is a term as soon as k is a multiple of 10 and belongs to A002957. In particular, a(4) <= 2*10^3020 - 1. - Max Alekseyev, Jun 07 2018
CROSSREFS
KEYWORD
base,more,nonn,bref
AUTHOR
Farideh Firoozbakht, Apr 28 2010
STATUS
approved