A292623 Number of median graphs on n nodes.

1, 1, 1, 3, 4, 11, 23, 69, 178, 567, 1741, 5890, 20005, 71294, 257889, 958595

Offset

1,4

Links

Table of n, a(n) for n=1..16.

Eric Weisstein's World of Mathematics, Median Graph

Example

n = 1: singleton graph K_1 (1 graph)
n = 2: P_2 = K_2 (1 graph)
n = 3: P_3 (1 graph)
n = 4: K_{1,3}, P_4, square graph P_2 X P_2 (3 graphs)
n = 5: banner graph, fork graph, P_5, S_5 = K_{1,4} (4 graphs)
Here, X denotes the graph Cartesian product

Crossrefs

Sequence in context: A219514 A131481 A001072 * A077900 A208176 A198443

Adjacent sequences: A292620 A292621 A292622 * A292624 A292625 A292626

Keyword

nonn,more

Author

Eric W. Weisstein, Sep 20 2017

Extensions

a(11)-a(16) from Brendan McKay, Apr 15 2019

Status

approved