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A031658 Numbers n such that continued fraction for sqrt(n) has odd period and central term 70. 0
1226, 61553, 99937, 100570, 101842, 150665, 209933, 276901, 356698, 360289, 362693, 363898, 443917, 446585, 449261, 454637, 651778, 659873, 661498, 664754, 768001, 769754, 771509, 773266, 778549, 780314, 782081, 1037165, 1041241, 1045325, 1049417 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

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

MATHEMATICA

cf70Q[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]] == 70]; Select[Range[11 10^5], cf70Q] (* Harvey P. Dale, Jul 24 2017 *)

CROSSREFS

Sequence in context: A218273 A046177 A031748 * A031533 A031713 A259998

Adjacent sequences:  A031655 A031656 A031657 * A031659 A031660 A031661

KEYWORD

nonn

AUTHOR

David W. Wilson

EXTENSIONS

Corrected and extended and definition clarified by Harvey P. Dale, Jul 24 2017

STATUS

approved

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Last modified February 24 04:30 EST 2020. Contains 332197 sequences. (Running on oeis4.)