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A031623 Numbers n such that continued fraction for sqrt(n) has odd period and central terms 35. 0
15178, 25681, 38537, 52153, 53069, 53993, 70981, 72586, 90289, 91493, 115961, 137341, 140317, 164554, 166993, 168629, 170273, 171098, 192469, 193346, 195989, 196874, 197761, 201329, 229213, 258905, 260941, 262985, 265037, 267097, 271241 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

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

MATHEMATICA

ct35Q[n_]:=Module[{s=Sqrt[n], cf, len, ctr}, If[IntegerQ[s], cf={1, 1}, cf= ContinuedFraction[ s][[2]]]; len=Length[cf]; ctr=Floor[len/2]; OddQ[len] && Take[cf, {ctr, ctr+1}]=={35, 35}]; Select[Range[280000], ct35Q] (* Harvey P. Dale, Apr 16 2013 *)

CROSSREFS

Sequence in context: A004975 A157436 A196495 * A105924 A259395 A233924

Adjacent sequences:  A031620 A031621 A031622 * A031624 A031625 A031626

KEYWORD

nonn

AUTHOR

David W. Wilson

EXTENSIONS

Corrected by Harvey P. Dale, Apr 16 2013

STATUS

approved

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Last modified April 26 04:11 EDT 2019. Contains 322469 sequences. (Running on oeis4.)