A031632 - OEIS

A031632

Numbers k such that the continued fraction for sqrt(k) has odd period and if the last term of the periodic part is deleted the two central terms are both 44.

485, 12569, 24074, 24698, 60637, 83113, 84269, 111781, 140914, 146213, 180137, 181837, 215737, 217597, 223225, 260629, 262673, 304226, 305329, 306434, 307541, 310874, 311989, 315346, 316469, 363133, 415577, 418157, 420745, 423341, 425945

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OFFSET

1,1

LINKS

Table of n, a(n) for n=1..31.

MATHEMATICA

cf44Q[n_]:=Module[{s=Sqrt[n], cf, len}, cf=If[IntegerQ[s], {1, 1}, ContinuedFraction[ s][[2]]]; len=Length[cf]; OddQ[len]&&cf[[(len+1)/2]] == 44]; Select[Range[426000], cf44Q] (* Harvey P. Dale, May 10 2020 *)

CROSSREFS

Sequence in context: A158326 A031722 A156774 * A097767 A031520 A235525

Adjacent sequences: A031629 A031630 A031631 * A031633 A031634 A031635

KEYWORD

nonn

AUTHOR

David W. Wilson

EXTENSIONS

First term 1937 removed by Georg Fischer, Jun 16 2019

First term (485) added and definition clarified by Harvey P. Dale, May 10 2020

STATUS

approved