OFFSET
0,2
EXAMPLE
E.g. 27 -> 1217 is prime.
MATHEMATICA
Select[Range[700], PrimeQ[FromDigits[Join[{1}, Riffle[ IntegerDigits[ #], 1]]]]&] (* Harvey P. Dale, Jul 24 2012 *)
CROSSREFS
KEYWORD
nonn,base,easy
AUTHOR
EXTENSIONS
More terms from Erich Friedman.
STATUS
approved