login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A213310 Numbers with exactly 3 nonprime substrings (substrings with leading zeros are considered to be nonprime). 1
10, 14, 16, 18, 40, 44, 46, 48, 49, 60, 64, 66, 68, 69, 80, 81, 84, 86, 88, 90, 91, 94, 96, 98, 99, 117, 123, 127, 132, 133, 135, 139, 153, 157, 167, 171, 172, 175, 177, 193, 211, 213, 217, 222, 225, 230, 234, 236, 238, 241 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The sequence is finite. Proof: Each 6-digit number has at least 4 nonprime substrings. Thus, each number with more than 6 digits has >= 4 nonprime substrings, too. Consequently, there is a boundary b<10^5, such that all numbers > b have more than 3 nonprime substrings.

The first term is a(1)=10=A213302(3). The last term is a(310)=73373=A213300(3).

LINKS

Hieronymus Fischer, Table of n, a(n) for n = 1..310

EXAMPLE

a(1)=10, since 10 has 3 nonprime substrings (0, 1, 10).

a(310)= 73373, since there are 3 nonprime substrings (33, 7337 and 73373).

CROSSREFS

Cf. A019546, A035232, A039996, A046034, A069489, A085823, A211681, A211682, A211684, A211685.

Cf. A035244, A079307, A213300 - A213321.

Sequence in context: A330210 A067188 A092632 * A055197 A116610 A289698

Adjacent sequences:  A213307 A213308 A213309 * A213311 A213312 A213313

KEYWORD

nonn,fini,base

AUTHOR

Hieronymus Fischer, Aug 26 2012

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified April 6 18:39 EDT 2020. Contains 333286 sequences. (Running on oeis4.)