OFFSET
1,1
FORMULA
Take 1297. 1*2 + 2*9 + 9*7 = 2 + 18 + 63 = 83, a prime.
MATHEMATICA
Select[Prime@Range[300], PrimeQ[Plus @@ Times @@@ Partition[IntegerDigits[ # ], 2, 1]] &] (* Ray Chandler, Mar 16 2007 *)
CROSSREFS
KEYWORD
nonn,base,easy
AUTHOR
J. M. Bergot, Mar 14 2007
EXTENSIONS
Corrected and extended by Ray Chandler, Mar 16 2007
STATUS
approved