A031623 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 35.

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

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

Subsequence of A003814.

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