A228377 Primes of the form XYYYYYYYX, where Y is a single digit.

188888881, 199999991, 322222223, 355555553, 722222227, 17333333317, 19555555519, 21444444421, 27888888827, 29111111129, 31333333331, 31555555531, 31666666631, 39444444439, 41999999941, 43222222243, 43666666643, 47999999947, 49333333349, 49555555549

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^(7 + len) n + 10^len Table[k (10^7 - 1) / 9, {k, 9}] + n, PrimeQ@#&]]; Array[f, 1000]//Flatten

Prog

(Magma) m:=7; [p: d in [1..9], n in [1..80 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: A061440 A064593 A084304 * A178565 A195902 A181321

Adjacent sequences: A228374 A228375 A228376 * A228378 A228379 A228380

Keyword

nonn,base

Author

Vincenzo Librandi, Sep 12 2013

Status

approved