A228376 Primes of the form XYYYYYYX, where Y is a single digit.

1711111117, 1766666617, 2388888823, 2399999923, 2911111129, 2933333329, 2955555529, 2966666629, 2999999929, 3188888831, 4111111141, 4133333341, 4144444441, 4188888841, 4322222243, 4333333343, 4377777743, 4388888843, 4399999943, 4744444447, 4766666647

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