OFFSET
1,1
COMMENTS
This is analogous to A172257, with increments in place of decrements.
EXAMPLE
23 comes from 2, explaining the first term. Until 983, no prime gives primes with concatenation of 5 and 7 numbers.
CROSSREFS
KEYWORD
base,nonn
AUTHOR
James G. Merickel, Feb 01 2010
STATUS
approved