A010338 Numbers k such that the continued fraction for sqrt(k) has period 7.

58, 73, 202, 250, 274, 314, 349, 425, 538, 761, 1010, 1073, 1130, 1301, 1546, 1745, 1825, 1898, 2050, 2173, 2258, 2330, 2482, 2581, 2777, 3161, 3202, 3554, 3877, 3890, 4106, 4133, 4346, 4586, 4925, 5162, 5261, 5273, 5297, 5305

Offset

1,1

Links

Chai Wah Wu, Table of n, a(n) for n = 1..10000 (terms n = 1..500 from Harvey P. Dale)

Mathematica

cfp7Q[n_]:=Module[{s=Sqrt[n]}, !IntegerQ[s]&&Length[ ContinuedFraction[ s][[2]]]==7]; Select[Range[6000], cfp7Q] (* Harvey P. Dale, Aug 11 2013 *)

Prog

(Python)
from sympy import continued_fraction_periodic
A010338_list = [n for n, s in ((i, continued_fraction_periodic(0, 1, i)[-1]) for i in range(1, 10**3)) if isinstance(s, list) and len(s) == 7] # Chai Wah Wu, Jun 08 2017

Crossrefs

Sequence in context: A224359 A226036 A127024 * A368615 A184074 A281824

Adjacent sequences: A010335 A010336 A010337 * A010339 A010340 A010341

Keyword

nonn

Author

N. J. A. Sloane, Walter Gilbert

Status

approved