OFFSET
1,2
COMMENTS
Only the digits 1, 3, 7 and 9 are in the sequence as a term ending in 0, 2, 4, 5, 6 or 8 would not be prime.
EXAMPLE
The first terms 1, 3, 7, 9, 71, 11, 13, 17,... form (when 2 successive digits are concatenated) the prime numbers 13, 37, 79, 97, 11, 11, 31, 17,...
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Eric Angelini and Jean-Marc Falcoz, Sep 05 2020
STATUS
approved