This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A307372 #20 Dec 05 2024 19:12:06 %S A307372 1,1,1,1,2,1,1,1,1,5,2,1,1,1,3,1,3,3,2,1,1,1,2,5,1,4,2,2,2,1,1,1,1,1, %T A307372 3,1,5,4,3,6,2,1,1,1,3,5,3,2,1,3,7,3,2,11,2,1,1,1,5,1 %N A307372 One half of the row length of A324251: one half of the length of the reduced principal cycle for discriminant 4*D(n), with D(n) = A000037(n). %C A307372 This is a subsequence of A226166. See the formula. %C A307372 For details on the cycles for the principal form F_p(n) = FR(n), the first reduced form of the not reduced Pell form F(n) = [1, 0, -D(n)], see A324251, also for references and a W. Lang link with Table 1, last column LCR(n) = 2*a(n). %F A307372 a(n) equals one half of the length of the reduced principal cycle of discriminant 4*D(n), with D(n) = A000037(n), for n >= 1. %F A307372 a(n) = A226166(e(n)), where e(n) is the n-th even term of A079896, for n >= 1. %Y A307372 Cf. A000037, A079896, A226166, A324251. %K A307372 nonn %O A307372 1,5 %A A307372 _Wolfdieter Lang_, Apr 19 2019