OFFSET
1,1
COMMENTS
The sequence is finite. Proof: Each 9-digit number has at least 15 nonprime substrings. Thus, each number with more than 9 digits has >= 15 nonprime substrings, too. Consequently, there is a boundary b<10^9, such that all numbers > b have more than 11 nonprime substrings.
LINKS
Hieronymus Fischer, Table of n, a(n) for n = 1..32869
EXAMPLE
a(1)= 10037, since 10037 has 11 nonprime substrings (0, 0, 1, 00, 03, 10, 003, 037, 100, 0037, 1003).
a(32869)= 82337397, since there are 11 nonprime substrings (8, 9, 33, 39, 82, 2337, 7397, 23373, 82337, 233739, 82337397).
CROSSREFS
KEYWORD
nonn,base,fini
AUTHOR
Hieronymus Fischer, Aug 26 2012
STATUS
approved