Irregular triangle read by rows. Properly color the vertices of a simple labeled graph on [n] using exactly n colors c_1<c_2<...<c_n (in other words, use each color exactly once). Orient the edges according to the strict order on the colors. T(n,k) is the number of such graphs with exactly k descents, n>=0, 0<=k<=binomial(n,2).

A381192

Irregular triangle read by rows. Properly color the vertices of a simple labeled graph on [n] using exactly n colors c_1<c_2<...<c_n (in other words, use each color exactly once). Orient the edges according to the strict order on the colors. T(n,k) is the number of such graphs with exactly k descents, n>=0, 0<=k<=binomial(n,2).