A108113 Numbers k such that the string 3137k is prime.

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

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 A339048

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