%I
%S 6,3,15,1,3,3,3,3,3,1,3,3,3,3,3,3,1,3,3,1,3,3,3,3,3,3
%N Denominator of 2*zeta_K(1) where K is the totally real field Q(sqrt(n)), as n runs through the squarefree numbers.
%D F. Hirzebruch, Hilbert modular surfaces, Ges. Abh. II, 225323.
%H F. Hirzebruch, <a href="http://www.maths.ed.ac.uk/~v1ranick/papers/hirzhilb.pdf">Hilbert modular surfaces</a>, L'Enseignement Math., 19 (1973), 183281. See p. 200.
%e 1/6, 1/3, 1/15, 1, 4/3, 7/3, 7/3, 1/3, 10/3, 4, ...
%Y Cf. A097916.
%K nonn,frac,more
%O 1,1
%A _N. J. A. Sloane_, Sep 04 2004
