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A108113 Numbers k such that the string 3137k is prime. 1
9, 11, 17, 21, 27, 39, 41, 63, 77, 83, 117, 137, 143, 159, 171, 179, 201, 209, 243, 257, 263, 311, 357, 371, 389, 399, 447, 461, 471, 507, 509, 513, 521, 531, 551, 567, 569, 573, 593, 609, 611, 623, 627, 663, 669, 681, 699, 723, 731, 747, 749, 777, 803, 837 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

31 and 37 are primes.

LINKS

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

EXAMPLE

If k=9, then 3137k = 31379 (prime).

If k=83, then 3137k = 313783 (prime).

MAPLE

a:=proc(n) local z: z:=nops(convert(n, base, 10)): if isprime(3137*10^z+n)=true then n else fi end: seq(a(n), n=1..1000); # Emeric Deutsch, Jul 02 2005

MATHEMATICA

Select[Range[900], PrimeQ[3137*10^IntegerLength[#]+#]&] (* Harvey P. Dale, Mar 19 2015 *)

PROG

(MAGMA) [ n: n in [1..900] | IsPrime(Seqint(Intseq(n) cat [7, 3, 1, 3])) ]; // Vincenzo Librandi, Feb 03 2011

CROSSREFS

Sequence in context: A048464 A075824 A228951 * A111391 A077788 A137018

Adjacent sequences:  A108110 A108111 A108112 * A108114 A108115 A108116

KEYWORD

nonn,base

AUTHOR

Parthasarathy Nambi, Jun 25 2005

EXTENSIONS

More terms from Emeric Deutsch, Jul 02 2005

STATUS

approved

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Last modified October 18 17:13 EDT 2019. Contains 328186 sequences. (Running on oeis4.)