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A031586 that the continued fraction for sqrt(k) has even period and if the last term of the periodic part is deleted the central term is 88. 0
7746, 7778, 7782, 7814, 7822, 7838, 7842, 7846, 7862, 7874, 7886, 7894, 7906, 7934, 7954, 7974, 7986, 8002, 8006, 8014, 8018, 8038, 8054, 8078, 8098, 17427, 17463, 17481, 17499, 17502, 17508, 17517, 17529, 17553, 17601, 17607, 17637, 17652, 17709 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..39.

MATHEMATICA

cf88Q[n_]:=Module[{s=Sqrt[n], cf, len}, cf=If[IntegerQ[s], {1}, ContinuedFraction[ s][[2]]]; len=Length[cf]; EvenQ[len]&&cf[[len/2]] == 88]; Select[ Range[18000], cf88Q] (* Harvey P. Dale, Sep 13 2018 *)

CROSSREFS

Sequence in context: A052099 A079035 A116317 * A116335 A115440 A321037

Adjacent sequences:  A031583 A031584 A031585 * A031587 A031588 A031589

KEYWORD

nonn

AUTHOR

David W. Wilson

STATUS

approved

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Last modified September 24 10:24 EDT 2021. Contains 347642 sequences. (Running on oeis4.)