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A228376 Primes of the form XYYYYYYX, where Y is a single digit. 1
1711111117, 1766666617, 2388888823, 2399999923, 2911111129, 2933333329, 2955555529, 2966666629, 2999999929, 3188888831, 4111111141, 4133333341, 4144444441, 4188888841, 4322222243, 4333333343, 4377777743, 4388888843, 4399999943, 4744444447, 4766666647 (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^(6 + len) n + 10^len Table[k (10^6 - 1) / 9, {k, 9}] + n, PrimeQ@#&]]; Array[f, 100] // Flatten

Select[With[{y=Table[PadRight[{}, 6, n], {n, 9}]}, FromDigits/@(Flatten[ Table[ Join[IntegerDigits[k], #, IntegerDigits[k]], {k, 1, 51, 2}]&/@y, 1])], PrimeQ]// Sort (* Harvey P. Dale, Mar 01 2019 *)

PROG

(MAGMA) m:=6; [p: d in [1..9], n in [1..70 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)]; //

CROSSREFS

Cf. A154270, A214290, A162423, A214702, A214291.

Sequence in context: A071372 A129474 A204347 * A015411 A034649 A211240

Adjacent sequences:  A228373 A228374 A228375 * A228377 A228378 A228379

KEYWORD

nonn,base

AUTHOR

Vincenzo Librandi, Sep 12 2013

STATUS

approved

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Last modified May 23 03:10 EDT 2019. Contains 323507 sequences. (Running on oeis4.)