

A031539


that the continued fraction for sqrt(k) has even period and if the last term of the periodic part is deleted the central term is 41.


0



1683, 1687, 1691, 1699, 1707, 1723, 1747, 1759, 1779, 1783, 1787, 1799, 1811, 1819, 1823, 1831, 1843, 1847, 6728, 6752, 6784, 6824, 6848, 6856, 6880, 6912, 6920, 6944, 6976, 7008, 7016, 7040, 7072, 7104, 7168, 7240, 7264, 7328, 7360, 7392, 15135, 15195
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OFFSET

1,1


COMMENTS

The "central term" is the term with an index equal to onehalf of the length of the continued fraction's period. For example, the "central term" of (1,2,3,4) is 2.  Harvey P. Dale, Nov 10 2017


LINKS



MATHEMATICA

ct41Q[n_]:=Module[{s=Sqrt[n], cf, len}, cf=If[IntegerQ[s], {1, 1, 1}, ContinuedFraction[ s][[2]]]; len=Length[cf]; EvenQ[len]&&cf[[len/2]] == 41]; Select[Range[16000], ct41Q] (* Harvey P. Dale, Nov 10 2017 *)


CROSSREFS



KEYWORD

nonn


AUTHOR



STATUS

approved



