|
|
A031687
|
|
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 99.
|
|
0
|
|
|
198997, 200785, 201682, 298237, 420073, 556741, 561226, 710938, 719393, 891497, 895277, 899065, 1086205, 1094557, 1098745, 1300129, 1311554, 1316138, 1533269, 1543189, 1545674, 1548161, 1553141, 1558129, 1560626, 1817833, 2062937
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
LINKS
|
|
|
MATHEMATICA
|
ct99Q[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]]] == cf[[Ceiling[len/2]]]==99]; Select[Range[2063000], ct99Q] (* Harvey P. Dale, Oct 09 2021 *)
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|