

A296621


Number of 5regular (quintic) connected graphs on 2*n nodes with diameter k written as irregular triangle T(n,k).


2



1, 0, 3, 0, 60, 0, 5457, 2391, 0, 258474, 3200871, 37, 1, 0, 1041762, 2583730089, 364670, 154, 0
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

3,3


COMMENTS

The results were found by applying the FloydWarshall algorithm to the output of Markus Meringer's GenReg program.


LINKS

Table of n, a(n) for n=3..21.
M. Meringer, GenReg, Generation of regular graphs.
Wikipedia, Distance (graph theory).
Wikipedia, FloydWarshall algorithm.


EXAMPLE

Triangle begins:
Diameter
n/ 1 2 3 4 5
6: 0 1
8: 0 3
10: 0 60
12: 0 5457 2391
14: 0 258474 3200871 37 1
16: 0 1041762 2583730089 364670 154
.
The adjacency matrix of the unique 5regular graph on 14 nodes with diameter 5 is provided as example in A296526.


CROSSREFS

Cf. A006821 (row sums), A068934, A204329, A296525 (number of terms in each row), A296526, A296620.
Sequence in context: A271762 A264882 A012759 * A120953 A009784 A276909
Adjacent sequences: A296618 A296619 A296620 * A296622 A296623 A296624


KEYWORD

nonn,tabf,more


AUTHOR

Hugo Pfoertner, Dec 19 2017


STATUS

approved



