OFFSET
1,1
LINKS
Harvey P. Dale, Table of n, a(n) for n = 1..1000
EXAMPLE
407 becomes 4(3)0(3)7 which is prime 43037.
MATHEMATICA
Select[Range[10, 600], PrimeQ[FromDigits[Riffle[IntegerDigits[#], 3]]]&] (* Harvey P. Dale, Dec 23 2023 *)
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Patrick De Geest, Aug 15 1999
STATUS
approved