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

 Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 59th year, we have over 358,000 sequences, and we’ve crossed 10,300 citations (which often say “discovered thanks to the OEIS”). Other ways to Give
 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A101215 Numbers n such that concatenation of n with 54321 is a prime. 1
 1, 10, 13, 28, 31, 37, 40, 44, 49, 55, 59, 68, 71, 77, 89, 94, 97, 100, 104, 115, 119, 121, 139, 140, 142, 145, 148, 161, 166, 178, 181, 191, 196, 199, 205, 226, 232, 233, 238, 241, 248, 251, 259, 260, 262, 272, 274, 290, 293, 295, 301, 313, 314, 317, 329, 331 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Conjecture 1 : for any integer N ending in 1 or 3 or 7 or 9 there is an infinite sequence of numbers n such that the concatenation nN is a prime. Conjecture 2 : for any integer N there is an infinite sequence of numbers n such that the concatenation Nn is a prime LINKS Harvey P. Dale, Table of n, a(n) for n = 1..1000 EXAMPLE 154321,1354321,2854321,3154321 ......... are primes MATHEMATICA Select[Range[400], PrimeQ[FromDigits[Join[IntegerDigits[#], {5, 4, 3, 2, 1}]]]&] (* Harvey P. Dale, Sep 28 2013 *) CROSSREFS Sequence in context: A074346 A126973 A220045 * A102249 A195313 A219829 Adjacent sequences: A101212 A101213 A101214 * A101216 A101217 A101218 KEYWORD nonn,base AUTHOR Pierre CAMI, Dec 14 2004 EXTENSIONS Inserted 10, 40, 100, 260 - R. J. Mathar, Nov 13 2009 STATUS approved

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

Last modified December 4 23:46 EST 2022. Contains 358572 sequences. (Running on oeis4.)