This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
For n=3, 18 digraph edge-sets (vertex 0 is the single global sink):
{21,10}
{20,10}
{22,21,10}
{22,20,10}
{21,12,10}
{21,11,10}
{20,12,10}
{22,21,12,10}
{22,21,11,10}
{22,20,12,10}
{22,20,11,10}
{21,20,12,10}
{21,12,11,10}
{20,11,12,10}
{22,21,20,12,10}
{22,21,12,11,10}
{22,20,12,11,10}
{22,21,20,12,11,10}.
// See Jim Snyder-Grant C code to generate and count digraphs with global sinks ./gsinks -l
\\ See PARI link in A350794 for program code. seq(n)={Vec(InitiallyV(GraphCIData(n,DigraphWithLoopEdges)))} \\ Andrew Howroyd, Jan 30 2022