OFFSET
1,1
MATHEMATICA
cf42Q[n_]:=Module[{s=Sqrt[n], cf, len}, cf=If[IntegerQ[s], {1, 2}, ContinuedFraction[s][[2]]]; len= Length[ cf]; OddQ[len]&&cf[[Floor[len/2]]]==cf[[Ceiling[len/2]]]==42]; Select[Range[ 450000], cf42Q] (* Harvey P. Dale, Aug 10 2023 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
EXTENSIONS
First term 1765 removed by Georg Fischer, Jun 16 2019
STATUS
approved