OFFSET
1,1
EXAMPLE
The number 715157 is prime and corresponds to n=15.
The number 7100510057 is prime and corresponds to n=1005.
MATHEMATICA
fQ[n_] := Block[{id = IntegerDigits[n]}, PrimeQ[ FromDigits[ Join[{7}, id, id, {7}]]]]; Select[ Range[1290], fQ[ # ] &] (* Robert G. Wilson v, Jan 14 2004 *)
CROSSREFS
KEYWORD
easy,nonn,base
AUTHOR
Mark Hudson (mrmarkhudson(AT)hotmail.com), Jan 13 2005
EXTENSIONS
More terms from Robert G. Wilson v, Jan 14 2005
STATUS
approved