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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 February 26 11:49 EST 2020. Contains 332279 sequences. (Running on oeis4.)