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Number of reduced indefinite binary forms of determinant -n.
(Formerly M0080)
1

%I M0080 #16 Jan 26 2019 05:46:50

%S 2,1,1,3,2,1,1,2,4,2,1,2,2,1,2,5,2,2,1,3,2,1,1,3,6,2,2,2,2,2,1,3,2,2,

%T 2,7,3,1,2,4,2,2,1,2,4,1,1,4,6,3,2,3,2,2,2,3,2,2,1,4,2,1,3,8,2,2,1,3,

%U 2,2

%N Number of reduced indefinite binary forms of determinant -n.

%D J. H. Conway and N. J. A. Sloane, "Sphere Packings, Lattices and Groups", Springer-Verlag, p. 362.

%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

%H Nachum Dershowitz, <a href="https://cs.uwaterloo.ca/journals/JIS/VOL20/Dershowitz/dersh3.html">Touchard’s Drunkard</a>, Journal of Integer Sequences, Vol. 20 (2017), #17.1.5.

%Y Cf. A006371, A006374.

%K nonn,hard

%O 1,1

%A _N. J. A. Sloane_.

%E Corrected Apr 15 1995