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A109356 Numbers k such that the string 235723572357k is prime. 1
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified April 20 22:22 EDT 2019. Contains 322310 sequences. (Running on oeis4.)