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A031750
Numbers k such that the least term in the periodic part of the continued fraction for sqrt(k) is 72.
1
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
KEYWORD
nonn
STATUS
approved