%I #22 Jan 20 2025 13:41:31
%S 2026,8102,18228,32404,50630,72906,99232,129608,164034,202510,245036,
%T 291612,342238,396914,455640,518416,585242,656118,731044,810020,
%U 893046,980122,1071248,1166424,1265650,1368926,1476252,1587628,1703054,1822530
%N Numbers k such that the least term in the periodic part of the continued fraction for sqrt(k) is 90.
%C A156856 is almost certainly a proper sequence of this sequence. - _Franklin T. Adams-Watters_, Feb 21 2009
%C In fact the first term not of the form A156856(n)=(45n)^2+n is a(93) = 17147972, with contfrac(sqrt(17147972)) = [4141; [91, 90, 91, 8282]]. - _M. F. Hasler_, Feb 21 2009
%C The first term not of the form A156856(n)=(45n)^2+n is a(93) = 17147972, with contfrac(sqrt(17147972)) = [4141; [91, 90, 91, 8282]]. - _M. F. Hasler_, Feb 21 2009
%H Charles R Greathouse IV, <a href="/A031768/b031768.txt">Table of n, a(n) for n = 1..10000</a>
%t cf90Q[n_]:=With[{s=Sqrt[n]},If[IntegerQ[s],1,Min[ContinuedFraction[s][[2]]]]==90]; Select[Range[1823000],cf90Q] (* _Harvey P. Dale_, Jan 20 2025 *)
%Y Cf. A156856.
%K nonn
%O 1,1
%A _David W. Wilson_