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A031512 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 14. 1
198, 206, 214, 238, 242, 246, 254, 444, 453, 471, 489, 501, 507, 516, 537, 543, 573, 788, 796, 844, 860, 876, 892, 908, 916, 924, 932, 940, 956, 964, 972, 988, 1004, 1020, 1230, 1245, 1255, 1270, 1345, 1355, 1405, 1420, 1470, 1505, 1545, 1555, 1595, 1770, 1866 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..1000

MATHEMATICA

cf14Q[n_]:=Module[{s=Sqrt[n], cf, len}, cf=If[IntegerQ[s], {1}, ContinuedFraction[s][[2]]]; len=Length[cf]; EvenQ[len]&&cf[[len/2]]==14]; Select[Range[2000], cf14Q] (* Harvey P. Dale, Apr 04 2013 *)

CROSSREFS

Sequence in context: A145452 A286853 A025375 * A260193 A025366 A248534

Adjacent sequences:  A031509 A031510 A031511 * A031513 A031514 A031515

KEYWORD

nonn

AUTHOR

David W. Wilson

STATUS

approved

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Last modified January 23 03:15 EST 2022. Contains 350504 sequences. (Running on oeis4.)