A031780 - OEIS

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A031780

Period of continued fraction for sqrt(n) contains exactly 12 ones.

211, 214, 382, 385, 393, 436, 457, 487, 501, 511, 524, 526, 553, 559, 581, 614, 657, 716, 749, 781, 831, 846, 856, 862, 869, 875, 881, 893, 950, 996, 1002, 1019, 1046, 1094, 1123, 1132, 1137, 1169, 1194, 1234, 1246, 1266, 1309, 1334, 1353, 1359, 1361, 1372

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OFFSET

1,1

LINKS

Table of n, a(n) for n=1..48.

MATHEMATICA

cf12Q[n_]:=Module[{s=Sqrt[n]}, If[IntegerQ[s], 1, Count[ ContinuedFraction[ s][[2]], 1]] == 12]; Select[Range[1500], cf12Q] (* Harvey P. Dale, Jul 21 2015 *)

CROSSREFS

Sequence in context: A037272 A013530 A020365 * A036232 A064826 A333012

Adjacent sequences: A031777 A031778 A031779 * A031781 A031782 A031783

KEYWORD

nonn

AUTHOR

David W. Wilson

STATUS

approved