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A213312 Numbers with exactly 5 nonprime substrings (substrings with leading zeros are considered to be nonprime). 1
101, 102, 105, 109, 110, 114, 116, 118, 120, 121, 124, 126, 128, 141, 142, 145, 149, 150, 154, 156, 158, 161, 162, 165, 181, 182, 185, 187, 189, 190, 194, 196, 198, 200, 201, 204, 206, 208, 209, 210, 214, 216, 218, 240 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
The sequence is finite. Proof: Each 7-digit number has at least 6 nonprime substrings. Thus, each number with more than 7 digits has >= 6 nonprime substrings, too. Consequently, there is a boundary b<10^6, such that all numbers > b have more than 5 nonprime substrings.
The first term is a(1)=101=A213302(5). The last term is a(1330)=831373=A213300(5).
LINKS
EXAMPLE
a(1)=101, since 101 has 5 nonprime substrings (0, 01, 1, 1, 10).
a(1330)= 831373, since there are 5 nonprime substrings (1, 8, 831, 8313, 31373).
CROSSREFS
Sequence in context: A134808 A274612 A261448 * A261021 A271642 A164849
KEYWORD
nonn,fini,base
AUTHOR
Hieronymus Fischer, Aug 26 2012
STATUS
approved

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Last modified April 24 03:08 EDT 2024. Contains 371918 sequences. (Running on oeis4.)