The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A125001 Non-insertable primes: primes with property that no matter where you insert (or prepend or append) a digit you get a composite number (except for prepending a zero). 2
 369293, 3823867, 5364431, 5409259, 7904521, 8309369, 9387527, 9510341, 22038829, 27195601, 28653263, 38696543, 39091441, 39113161, 43744697, 45095839, 45937109, 48296921, 48694231, 49085093, 49106677, 50791927 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Is the sequence infinite? - Zak Seidov, Nov 14 2014 LINKS David W. Wilson and Zak Seidov, Table of n, a(n) for n = 1..3000 Jeremiah T. Southwick, Two Inquiries Related to the Digits of Prime Numbers, Ph. D. Dissertation, University of South Carolina (2020). EXAMPLE 369293 is a member because all of 1369293, 2369293, 3369293, ..., 3069293, 3169293, ..., 3692930, ..., 3692939 are composite. MATHEMATICA nipQ[x_]:=Module[{id=IntegerDigits[x], len}, len=Length[id]; AllTrue[ Select[ Flatten[Table[FromDigits[Insert[id, n, i]], {i, len+1}, {n, 0, 9}], 1], #!=x&], CompositeQ]]; Select[ Prime[Range[3050000]], nipQ] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Apr 12 2018 *) CROSSREFS Sequence in context: A156115 A199496 A234048 * A172563 A172582 A172682 Adjacent sequences:  A124998 A124999 A125000 * A125002 A125003 A125004 KEYWORD nonn,base AUTHOR David W. Wilson, Jan 08 2007 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.

Last modified January 21 09:34 EST 2022. Contains 350476 sequences. (Running on oeis4.)