|
|
A031613
|
|
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 25.
|
|
0
|
|
|
1453, 7793, 13306, 13537, 19165, 20285, 28393, 35569, 37861, 46514, 47378, 47813, 57961, 58925, 60877, 83473, 84629, 85793, 86378, 88738, 100481, 101114, 101749, 104309, 104954, 105601, 114973, 116329, 123229, 131885, 133337, 134797, 136265, 139225
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
LINKS
|
|
|
MATHEMATICA
|
cf25Q[n_]:=Module[{s=Sqrt[n], c, len}, c=If[IntegerQ[s], {0, 0}, ContinuedFraction[ s][[2]]]; len=Length[c]; OddQ[len] && c[[Floor[ len/2]+ 1]] == 25]; Select[Range[140000], cf25Q] (* Harvey P. Dale, Nov 22 2013 *)
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|