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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
Sequence in context: A068280 A020396 A052237 * A289822 A145529 A203393
KEYWORD
nonn
AUTHOR
EXTENSIONS
Corrected and extended by Harvey P. Dale, Nov 22 2013
STATUS
approved

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Last modified February 23 02:15 EST 2024. Contains 370265 sequences. (Running on oeis4.)