%I #16 Mar 05 2020 22:52:51
%S 4,13,13,40,122,40,121,1042,1042,121,364,8683,23544,8683,364,1093,
%T 72271,510835,510835,72271,1093
%N Triangle read by rows: T(n,k) (n >= 2, 1 <= k <= n-1) = Euclidean distance degree of variety of n X n matrices of rank <= k.
%C Column 1 appears to follow the recurrence T(n, 1) = 3*T(n-1, 1) + 1 (A003462, all ones in base 3). - _Georg Fischer_, Mar 05 2020
%H J. Draisma, E. Horobet, G. Ottaviani, B. Sturmfels and R. K. Thomas, <a href="http://arxiv.org/abs/1309.0049">The Euclidean distance degree of an algebraic variety</a>, arXiv preprint arXiv: 1309.0049 [math.AG], 2013-2014, p. 24.
%e Triangle begins:
%e 4;
%e 13, 13;
%e 40, 122, 40;
%e 121, 1042, 1042, 121;
%e 364, 8683, 23544, 8683, 364;
%e 1093, 72271, 510835, 510835, 72271, 1093;
%e ...
%Y Cf. A003462.
%K nonn,tabl,more
%O 2,1
%A _N. J. A. Sloane_, Dec 03 2013