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 A031662 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 74. 0
 1370, 12553, 34621, 111637, 166585, 169865, 312706, 400978, 403514, 501625, 504461, 611965, 728138, 731554, 743573, 858101, 859954, 861809, 867386, 869249, 872981, 876721, 1158617, 1162925, 1167241, 1171565, 1180237, 1323461, 1328065, 1332677, 1339610 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Table of n, a(n) for n=1..31. MATHEMATICA cf74Q[n_]:=Module[{s=Sqrt[n], cf, len}, cf=If[IntegerQ[s], {2, 2}, ContinuedFraction[ s][[2]]]; len=Length[cf]; OddQ[len] && cf[[(len+1)/2]]==74]; Select[Range[1400000], cf74Q] (* Harvey P. Dale, Mar 15 2015 *) CROSSREFS Sequence in context: A145697 A045107 A031752 * A251567 A251562 A059082 Adjacent sequences: A031659 A031660 A031661 * A031663 A031664 A031665 KEYWORD nonn AUTHOR David W. Wilson EXTENSIONS Definition clarified and terms corrected and extended by Harvey P. Dale, Mar 15 2015 STATUS approved

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Last modified June 5 04:55 EDT 2023. Contains 363130 sequences. (Running on oeis4.)