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A031520 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 22. 0
486, 498, 502, 514, 526, 534, 542, 562, 566, 574, 1092, 1101, 1119, 1137, 1149, 1191, 1209, 1236, 1257, 1263, 1281, 1293, 1940, 1948, 1964, 1972, 1996, 2012, 2036, 2044, 2060, 2076, 2084, 2092, 2108, 2124, 2132, 2140, 2156, 2164, 2188, 2204, 2220, 2228 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..44.

MATHEMATICA

cf22Q[n_]:=Module[{s=Sqrt[n], cf, len}, cf=If[IntegerQ[s], {1}, ContinuedFraction[ s][[2]]]; len=Length[cf]; EvenQ[len]&&cf[[len/2]] == 22]; Select[Range[2300], cf22Q] (* Harvey P. Dale, Jul 07 2020 *)

CROSSREFS

Sequence in context: A156774 A031632 A097767 * A235525 A249227 A130181

Adjacent sequences:  A031517 A031518 A031519 * A031521 A031522 A031523

KEYWORD

nonn

AUTHOR

David W. Wilson

STATUS

approved

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Last modified May 27 02:38 EDT 2022. Contains 354092 sequences. (Running on oeis4.)