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 A031674 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 86. 0
 1850, 16909, 46681, 91253, 151402, 224797, 226697, 313769, 316013, 417541, 425329, 537578, 540514, 676045, 682637, 984593, 990554, 994538, 1158401, 1162709, 1171349, 1180021, 1182194, 1364953, 1374313, 1563341, 1568345, 1573357, 1780517, 1783186, 1785857 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Table of n, a(n) for n=1..31. MATHEMATICA cfo86Q[n_]:=Module[{s=Sqrt[n], cf, len}, cf=If[IntegerQ[s], {0, 0}, ContinuedFraction[ s][[2]]]; len=Length[cf]; OddQ[len]&&cf[[(len+1)/2]] == 86]; Select[Range[1800000], cfo86Q] (* Harvey P. Dale, Jul 31 2013 *) CROSSREFS Sequence in context: A062670 A206468 A031764 * A031541 A031721 A224567 Adjacent sequences: A031671 A031672 A031673 * A031675 A031676 A031677 KEYWORD nonn AUTHOR David W. Wilson EXTENSIONS Corrected and extended by Harvey P. Dale, Jul 31 2013 STATUS approved

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Last modified December 4 07:50 EST 2023. Contains 367557 sequences. (Running on oeis4.)