OFFSET
1,1
MATHEMATICA
cf69Q[n_]:=Module[{s=Sqrt[n], cf, len}, cf=If[IntegerQ[s], {1}, ContinuedFraction[ s][[2]]]; len= Length[ cf]; EvenQ[len]&&cf[[len/2]]==69]; Select[Range[20000], cf69Q] (* Harvey P. Dale, Jul 06 2019 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved