OFFSET
1,1
COMMENTS
There can be no prime whose middle three digits are "000" because it would equal X*(10^Floor[Log[10,X]+1] + 1). - Robert G. Wilson v, Jul 11 2009
LINKS
Robert G. Wilson v, Table of n, a(n) for n = 1..10895
MATHEMATICA
f[n_] := Block[{len = Floor[ Log[10, n] + 1]}, Select[10^(3 + len) n + 10^len*Table[k (10^3 - 1)/9, {k, 9}] + n, PrimeQ@# &]]; Array[f, 31] // Flatten (* Robert G. Wilson v, Jul 11 2009 *)
Select[FromDigits/@Flatten[Table[Join[IntegerDigits[x], PadRight[{}, 3, y], IntegerDigits[ x]], {x, 40}, {y, Range[9]}], 1], PrimeQ] (* Harvey P. Dale, Jun 28 2020 *)
PROG
(Magma) m:=3; [p: d in [1..9], n in [1..40 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)]; // Vincenzo Librandi, Sep 14 2013
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Vincenzo Librandi, Jul 03 2009
STATUS
approved