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A322700 Number of unlabeled graphs with loops spanning n vertices. 31
1, 1, 4, 14, 70, 454, 4552, 74168, 2129348, 111535148, 10812483376, 1945437208224, 650378721156736, 404749938336404704, 470163239887698967104, 1022592854829028311090816, 4177826139658552046627175072, 32163829440870460348768023969632 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,3
COMMENTS
The span of a graph is the union of its edges. The not necessarily spanning case is A000666.
LINKS
FORMULA
First differences of A000666.
MATHEMATICA
Table[Sum[2^PermutationCycles[Ordering[Map[Sort, Select[Tuples[Range[n], 2], OrderedQ]/.Rule@@@Table[{i, prm[[i]]}, {i, n}], {1}]], Length], {prm, Permutations[Range[n]]}]/n!, {n, 0, 8}]//Differences (* Mathematica 8.0+ *)
CROSSREFS
Sequence in context: A050549 A222980 A321273 * A167144 A159483 A088127
KEYWORD
nonn
AUTHOR
Gus Wiseman, Dec 23 2018
STATUS
approved

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Last modified March 28 04:13 EDT 2024. Contains 371235 sequences. (Running on oeis4.)