This site is supported by donations to The OEIS Foundation.

 Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing. Other ways to donate

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified December 6 04:14 EST 2019. Contains 329784 sequences. (Running on oeis4.)