|
|
A031616
|
|
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 28.
|
|
0
|
|
|
5209, 16210, 16465, 16981, 24457, 35513, 45169, 46021, 58853, 59338, 60314, 72185, 74345, 75437, 92857, 106154, 107458, 108113, 110753, 123826, 124529, 125941, 127361, 128074, 128789, 131669, 151273, 168941, 170585, 172237, 173897
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
LINKS
|
|
|
MATHEMATICA
|
cf28Q[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]] == 28]; Rest[Select[Range[174000], cf28Q]] (* Harvey P. Dale, Jun 24 2020 *)
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|