A109356 Numbers k such that the string 235723572357k is prime.

1, 31, 59, 83, 97, 157, 193, 197, 233, 289, 347, 367, 409, 431, 439, 443, 547, 683, 701, 731, 733, 769, 781, 787, 797, 839, 877, 961, 1019, 1039, 1061, 1123, 1177, 1181, 1213, 1249, 1277, 1283, 1301, 1349, 1373, 1423, 1457, 1579, 1649, 1667, 1721

Offset

1,2

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Example

If k=1 then 235723572357k = 2357235723571 (prime).
If k=289 then 235723572357k = 235723572357289 (prime).

Mathematica

Select[Range[2000], PrimeQ[235723572357*10^IntegerLength[#]+#]&] (* Harvey P. Dale, Aug 10 2017 *)

Prog

(Magma) [ n: n in [1..1750] | IsPrime(Seqint(Intseq(n) cat [7, 5, 3, 2, 7, 5, 3, 2, 7, 5, 3, 2])) ]; // Vincenzo Librandi, Feb 02 2011

Crossrefs

Sequence in context: A096453 A218794 A218771 * A061251 A166604 A039350

Adjacent sequences: A109353 A109354 A109355 * A109357 A109358 A109359

Keyword

nonn,base

Author

Parthasarathy Nambi, Aug 22 2005

Status

approved