A031522 Numbers k such 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 24.

578, 594, 614, 622, 642, 662, 674, 1299, 1317, 1329, 1374, 1389, 1401, 1407, 1437, 1461, 1473, 1497, 1509, 1518, 2308, 2348, 2364, 2372, 2380, 2396, 2404, 2412, 2428, 2444, 2452, 2460, 2468, 2476, 2492, 2508, 2516, 2524, 2540, 2564, 2572, 2588, 2612

Offset

1,1

Links

Table of n, a(n) for n=1..43.

Mathematica

cf24Q[n_]:=Module[{s=Sqrt[n], cf, len}, cf=If[IntegerQ[s], {1}, ContinuedFraction[ s] [[2]]]; len=Length[cf]; EvenQ[len]&&cf[[len/2]]==24]; Select[Range[2700], cf24Q] (* Harvey P. Dale, Feb 09 2023 *)

Crossrefs

Sequence in context: A097770 A252377 A252376 * A234500 A252384 A252385

Adjacent sequences: A031519 A031520 A031521 * A031523 A031524 A031525

Keyword

nonn

Author

David W. Wilson

Status

approved