A031586 - OEIS

A031586

Numbers k such 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.

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

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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