login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A296621 Number of 5-regular (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 Floyd-Warshall 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, Floyd-Warshall 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 5-regular 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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified August 1 13:01 EDT 2021. Contains 346391 sequences. (Running on oeis4.)