OFFSET
1,1
COMMENTS
EXAMPLE
861 is in the sequence because 861=41*(2*10^1+1); (2*10^1+1)/3=7 and 7 is prime.
MATHEMATICA
Do[If[PrimeQ[(2*10^n + 1)/3], Print[41*(2*10^n + 1)]], {n, 63}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Farideh Firoozbakht, Apr 16 2005
STATUS
approved