%I
%S 1,0,1,1,0,0,1,4,4,1,1,0,0,0,1,11,31,45,38,27,13,5,1,1,0,0,0,0,1,23,
%T 152,486,992,1419,1641,1485,1152,707,379,154,61,16,5,1,1
%N Triangle T(n,k) of number of digraphs with a source and a sink on n unlabeled nodes and k arcs, k=0,1,..,n*(n1).
%D V. Jovovic, G. Kilibarda, Enumeration of labeled initiallyfinally connected digraphs, Scientific review, Serbian Scientific Society, 1920 (1996), p. 246.
%e [1],[0,1,1],[0,0,1,4,4,1,1],[0,0,0,1,11,31,45,38,27,13,5,1,1],...; Number of digraphs with a source and a sink on 3 unlabeled nodes is 11=1+4+4+1+1.
%Y Row sums give A049531. Cf. A057270A057277, A057279.
%K more,nonn,tabf
%O 1,8
%A _Vladeta Jovovic_, Goran Kilibarda, Sep 14 2000
