login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A054923 Triangle read by rows: number of connected graphs with k >= 0 edges and n nodes (1<=n<=k+1). 5
1, 0, 1, 0, 0, 1, 0, 0, 1, 2, 0, 0, 0, 2, 3, 0, 0, 0, 1, 5, 6, 0, 0, 0, 1, 5, 13, 11, 0, 0, 0, 0, 4, 19, 33, 23, 0, 0, 0, 0, 2, 22, 67, 89, 47, 0, 0, 0, 0, 1, 20, 107, 236, 240, 106, 0, 0, 0, 0, 1, 14, 132, 486, 797, 657, 235, 0, 0, 0, 0, 0, 9, 138, 814, 2075, 2678, 1806, 551, 0, 0, 0, 0, 0, 2, 95, 1454, 8404, 22950, 33851, 28908, 1301 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

0,10

COMMENTS

The diagonal n = k+1 is A000055(n). - Jonathan Vos Post, Aug 10 2008

REFERENCES

G. A. Baker et al., High-temperature expansions for the spin-1/2 Heisenberg model, Phys. Rev., 164 (1967), 800-817.

F. Harary and E. M. Palmer, Graphical Enumeration, Academic Press, NY, 1973, p. 93, Table 4.2.2; p. 241, Table A2.

LINKS

Table of n, a(n) for n=0..90.

R. J. Mathar, Statistics on Small Graphs, arXiv:1709.09000 (2017), Table 57.

Gordon Royle, Small graphs

EXAMPLE

1;

0 1;

0 0 1;

0 0 1 2;

0 0 0 2 3;

0 0 0 1 5 6;

... (so with 5 edges there's 1 graph with 4 nodes, 5 with 5 nodes and 6 with 6 nodes). [Typo corrected by Anders Haglund, Jul 08 2008]

CROSSREFS

Cf. A002905 (row sums), A001349 (column sums), A008406, A046751 (transpose), A054924 (transpose), A046742 (w/o left column).

Sequence in context: A275964 A284272 A175070 * A263145 A057108 A063958

Adjacent sequences:  A054920 A054921 A054922 * A054924 A054925 A054926

KEYWORD

nonn,easy,nice,tabl

AUTHOR

N. J. A. Sloane.

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 | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified November 21 11:54 EST 2018. Contains 317447 sequences. (Running on oeis4.)