A108334 Numbers k such that the string 10197k is prime.

7, 13, 17, 23, 29, 31, 41, 47, 71, 83, 101, 107, 137, 157, 169, 193, 197, 217, 221, 223, 259, 301, 347, 373, 389, 391, 403, 427, 437, 469, 491, 497, 511, 527, 559, 563, 581, 587, 613, 631, 653, 673, 679, 683, 689, 701, 703, 727, 743, 749, 757, 799, 827, 833, 857, 893, 899, 907, 917

Offset

1,1

Comments

101 and 97 are primes.

Links

Michael De Vlieger, Table of n, a(n) for n = 1..10000

Example

k=7 and k=83 are in the sequence because 10197k = 101977 and 10197k = 1019783 are prime.

Mathematica

Select[Range[10^3], PrimeQ[10197*10^IntegerLength[#] + #] &] (* Michael De Vlieger, Jan 22 2018 *)

Prog

(Magma) [ n: n in [1..1750] | IsPrime(Seqint(Intseq(n) cat [7, 9, 1, 0, 1])) ]; // Vincenzo Librandi, Feb 02 2011

Crossrefs

Sequence in context: A226138 A180263 A002733 * A288713 A136083 A167276

Adjacent sequences: A108331 A108332 A108333 * A108335 A108336 A108337

Keyword

nonn,base

Author

Parthasarathy Nambi, Jun 30 2005

Status

approved