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 A108114 Numbers n such that the string 3731n is the decimal expansion of a prime number. 2
 3, 27, 51, 57, 71, 81, 83, 87, 93, 99, 107, 137, 141, 173, 207, 209, 213, 237, 251, 257, 303, 311, 333, 341, 393, 417, 443, 447, 461, 473, 477, 489, 491, 509, 513, 521, 527, 531, 549, 557, 579, 591, 593, 603, 621, 627, 683, 701, 711, 713, 731, 737, 747, 759 (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 3 is in the sequence because 37313 is prime. 99 is in the sequence because 373199 is prime. 207 is in the sequence because 3731207 is prime. MAPLE a:=proc(n) local z: z:=nops(convert(n, base, 10)): if isprime(3731*10^z+n)=true then n else fi end: seq(a(n), n=1..1000); # Emeric Deutsch, Jul 04 2005 MATHEMATICA Select[Range[1000], PrimeQ[3731*10^IntegerLength[#]+#]&] (* Harvey P. Dale, Aug 26 2013 *) PROG (Magma) [ n: n in [1..800] | IsPrime(Seqint(Intseq(n) cat [1, 3, 7, 3])) ]; CROSSREFS Sequence in context: A175545 A032418 A108163 * A172969 A147267 A071183 Adjacent sequences: A108111 A108112 A108113 * A108115 A108116 A108117 KEYWORD nonn,base AUTHOR Parthasarathy Nambi, Jun 25 2005 EXTENSIONS More terms from Emeric Deutsch, Jul 04 2005 STATUS approved

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Last modified March 23 03:46 EDT 2023. Contains 361434 sequences. (Running on oeis4.)