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A031514 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 16. 0
258, 262, 278, 302, 322, 579, 597, 633, 651, 654, 669, 681, 687, 717, 726, 1028, 1052, 1060, 1068, 1076, 1084, 1108, 1116, 1124, 1132, 1148, 1164, 1172, 1212, 1228, 1244, 1252, 1268, 1276, 1292, 1605, 1630, 1645, 1655, 1670, 1795, 1805, 1830, 1895, 1905 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..45.

MATHEMATICA

cf16Q[n_]:=Module[{s=Sqrt[n], cf, len}, cf=If[IntegerQ[s], {1}, ContinuedFraction[ s][[2]]]; len=Length[cf]; EvenQ[len] && cf[[len/2]] == 16]; Select[Range[2000], cf16Q] (* Harvey P. Dale, Mar 04 2018 *)

CROSSREFS

Sequence in context: A121237 A161683 A250741 * A173981 A339538 A252264

Adjacent sequences:  A031511 A031512 A031513 * A031515 A031516 A031517

KEYWORD

nonn

AUTHOR

David W. Wilson

STATUS

approved

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Last modified November 29 05:05 EST 2021. Contains 349416 sequences. (Running on oeis4.)