OFFSET
1,1
MATHEMATICA
okQ[n_]:=Module[{dc3=DigitCount[n, 9, 3]}, dc3>0&&dc3==DigitCount[n, 9, 7]]
Select[Range[2000], okQ] (* Harvey P. Dale, Nov 26 2010 *)
CROSSREFS
KEYWORD
nonn,base,easy
AUTHOR
EXTENSIONS
More terms from Harvey P. Dale, Nov 26 2010
STATUS
approved