OFFSET
1,1
COMMENTS
The sequence is finite. Proof: Each 8-digit number has at least 10 nonprime substrings. Thus each number with more than 8 digits has >= 10 nonprime substrings, too. Consequently there is a boundary b<10^7 such that all numbers > b have more than 9 nonprime substrings.
LINKS
Hieronymus Fischer, Table of n, a(n) for n = 1..12411
EXAMPLE
a(1) = 1002 is in the sequence, since 1002 has 9 nonprime substrings (0, 0, 1, 00, 02, 10, 002, 100, 1002).
a(12411) = 9973331 is in the sequence since there are 9 nonprime substrings (1, 9, 9, 33, 33, 99, 333, 973, 97333).
CROSSREFS
KEYWORD
nonn,base,fini
AUTHOR
Hieronymus Fischer, Aug 26 2012
STATUS
approved