%I #18 Oct 20 2019 01:59:24
%S 0,1,2,3,7,9,13,19,23,27,35,41,43,45,53,55,71,77,101,127,129,135,147,
%T 163,169,189,199,201,247,283,335,353,367,459,465,503,537,587,625,637,
%U 643,739,767,827,1009,1135,1325,1423,1433,1543,1561
%N Periods, n, of square root continued fractions at which A013646 increases.
%C Each term of this sequence takes a turn at being the smallest unknown period for a square root continued fraction. Periods 1 and 2 are seen as the periods of sqrt(2) and sqrt(3) respectively, but a period of 3 is not seen until sqrt(41).
%C By convention, the period for perfect squares (e.g., 1) is 0.
%C Open question: Are there any more even terms after the 2?
%H Patrick McKinley, <a href="/A215485/b215485.txt">Table of n, a(n) for n = 0..254</a>
%e When a square root continued fraction with a period of 3 is first seen (at sqrt(41)), the lowest period not yet seen is 7, which first occurs as the period of sqrt(58).
%Y Cf. A013646.
%K nonn
%O 0,3
%A _Patrick McKinley_, Aug 12 2012