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 A031667 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 79. 0
 39229, 128245, 191965, 268493, 355441, 357829, 451873, 458618, 565865, 568877, 571897, 689341, 832273, 843253, 976769, 984689, 986674, 988661, 992641, 994634, 996629, 998626, 1149913, 1327945, 1332557, 1504037, 1508945, 1513861, 1526186, 1531130, 1536082 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS MATHEMATICA op79Q[n_]:=Module[{s=Sqrt[n], cf, len}, cf=If[IntegerQ[s], {1, 1}, ContinuedFraction[ s][[2]]]; len=Length[cf]; OddQ[len] && cf[[Floor[ len/2]+1]] == 79]; Select[Range[1600000], op79Q] (* Harvey P. Dale, Aug 04 2013 *) CROSSREFS Sequence in context: A224622 A233955 A250515 * A196200 A274128 A144306 Adjacent sequences:  A031664 A031665 A031666 * A031668 A031669 A031670 KEYWORD nonn AUTHOR EXTENSIONS Corrected and extended by Harvey P. Dale, Aug 04 2013 STATUS approved

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Last modified December 5 10:11 EST 2021. Contains 349543 sequences. (Running on oeis4.)