A031750 Numbers k such that the least term in the periodic part of the continued fraction for sqrt(k) is 72.

1297, 5186, 11667, 20740, 32405, 46662, 63511, 82952, 104985, 129610, 156827, 186636, 219037, 254030, 291615, 331792, 374561, 419922, 467875, 518420, 571557, 627286, 685607, 746520, 810025, 876122, 944811, 1016092, 1089965, 1166430

Offset

1,1

Comments

a(n) = 1296n^2 + n for n < 75, but a(75) = 7102298. - Charles R Greathouse IV, Aug 04 2017

Links

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

Mathematica

cf72Q[n_]:=Module[{s=Sqrt[n]}, If[IntegerQ[s], 1, Min[ContinuedFraction[s][[2]]]]==72]; Select[Range[12*10^5], cf72Q] (* Harvey P. Dale, Jul 15 2020 *)

Crossrefs

Sequence in context: A013841 A358648 A256834 * A345956 A031534 A252468

Adjacent sequences: A031747 A031748 A031749 * A031751 A031752 A031753

Keyword

nonn

Author

David W. Wilson

Status

approved