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A351052
Number of unlabeled digraphs with n nodes containing a global sink (or source), self-loops allowed.
0
1, 2, 18, 440, 32404, 7423456, 5473328160, 13430706072192, 113086387825668384, 3345639802029563258880, 353900830082830194441001984, 135600928084762756427776332541952, 190092581374833963606044859875698932736, 982736440685354936080688846774429648871161856
OFFSET
1,2
LINKS
EXAMPLE
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}.
PROG
(C) \\ See Jim Snyder-Grant C code to generate and count digraphs with global sinks ./gsinks -l
(PARI) \\ See PARI link in A350794 for program code.
seq(n)={Vec(InitiallyV(GraphCIData(n, DigraphWithLoopEdges)))} \\ Andrew Howroyd, Jan 30 2022
CROSSREFS
Cf. A350360 (self-loops not allowed).
Sequence in context: A374278 A260656 A141074 * A082402 A208055 A306655
KEYWORD
nonn
AUTHOR
Jim Snyder-Grant, Jan 30 2022
EXTENSIONS
Terms a(8) and beyond from Andrew Howroyd, Jan 30 2022
STATUS
approved