A326252 Number of digraphs with vertices {1..n} whose increasing edges are crossing.

0, 0, 0, 0, 16384, 22020096, 62679678976, 556181084962816

Offset: 0

Author

Gus Wiseman, Jun 30 2019

Keywords

• nonn
• more

Comments

A directed edge (a,b) is increasing if a < b. Two edges (a,b), (c,d) are crossing if a < c < b < d or c < a < d < b.

Crossrefs

Simple graphs whose edges are crossing are A326210.

Digraphs whose increasing edges are not crossing are A326251.

Digraphs whose edges are not crossing are A326237.

Cf. A002416, A002720, A229865, A324170, A326209, A326252, A326258.

Programs

Mathematica

croXQ[eds_]:=MatchQ[eds,{_,{x_,y_},_,{z_,t_},_}/;x
				

Formula

a(n) = 2^(n * (n + 1)/2) * A326210(n).