

A003317


Number of unlabeled minimally 2connected graphs with n nodes (also called "blocks").
(Formerly M0799)


4



1, 1, 2, 3, 6, 12, 28, 68, 184, 526, 1602, 5075, 16711, 56428, 195003, 685649, 2447882, 8850157, 32359428, 119492766, 445236635, 1672636369, 6331624545, 24138404479, 92640942148, 357805122286, 1390318899884, 5433781135206
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OFFSET

3,3


COMMENTS

Pootheri reference also contains the edge breakups for each term.


REFERENCES

A. M. Hobbs, A catalog of minimal blocks, J. Res. National Bureau Standards, B 77 (1973), 5360.
S. K. Pootheri, Characterizing and counting classes of unlabeled 2connected graphs, Ph. D. Dissertation, University of Georgia. (Under the direction of Robert W. Robinson, rwr(AT)cs.uga.edu)
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).


LINKS

Table of n, a(n) for n=3..30.
A. M. Hobbs, A catalog of minimal blocks, J. Res. National Bureau Standards, B 77 (1973), 5360. (Annotated scanned copy)
Hu, Guan Zhang; Liu, Guo Qing; Liu, Shi; He, Jian Ping; Enumeration of minimally 2connected graphs by means of group theory, (Chinese) Acta Math. Appl. Sinica 12 (1989), no. 2, 164173.


CROSSREFS

Cf. A054316, A054317, A002218.
Sequence in context: A014280 A073431 A273873 * A145062 A300323 A261230
Adjacent sequences: A003314 A003315 A003316 * A003318 A003319 A003320


KEYWORD

nonn,nice


AUTHOR

N. J. A. Sloane.


EXTENSIONS

More terms from Sridar K. Pootheri (sridar(AT)math.uga.edu), Feb 25 2000


STATUS

approved



