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A214291 Primes of the form XYYYYYX, where Y is a single digit. 5
1333331, 1444441, 1777771, 3222223, 3444443, 7666667, 9222229, 9888889, 134444413, 136666613, 137777713, 191111119, 196666619, 197777719, 232222223, 295555529, 311111131, 319999931, 331111133, 379999937, 392222239, 394444439 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

MATHEMATICA

f[n_]:=Block[{len=Floor[Log[10, n]+1]}, Select[10^(5+len) n+10^len*Table[k (10^5-1)/9, {k, 9}]+n, PrimeQ@#&]]; Array[f, 3509]//Flatten

PROG

(MAGMA) m:=5; [p: d in [1..9], n in [1..50 by 2] | IsPrime(p) where p is n*(10^(m+t)+1)+d*10^t*(10^m-1) div 9 where t is #Intseq(n)]; // Bruno Berselli, Sep 12 2013

CROSSREFS

Cf. A154270, A162423, A214290.

Sequence in context: A204969 A237107 A206620 * A023047 A206254 A157854

Adjacent sequences:  A214288 A214289 A214290 * A214292 A214293 A214294

KEYWORD

nonn,base

AUTHOR

Vincenzo Librandi, Jul 26 2012

STATUS

approved

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Last modified February 22 21:45 EST 2018. Contains 299469 sequences. (Running on oeis4.)