|
Search: id:A058737
|
|
| |
|
| 1, 1, 3, 7, 20, 55, 162, 477, 1450, 4446, 13858, 43589, 138515, 443487, 1430261, 4640312, 15137893, 49620637, 163360133, 539904503, 1790699059, 5958280016, 19883532941, 66532519727, 223177199775, 750340752081, 2528058240115
(list; graph; listen)
|
|
|
OFFSET
|
2,3
|
|
|
COMMENT
|
Also the number of unlabeled cographs on n nodes with two components. - Vladeta Jovovic (vladeta(AT)eunet.rs), May 07 2005
|
|
REFERENCES
|
J. Riordan, The blossoming of Schroeder's fourth problem, Acta Math., 137 (1976), 1-16.
|
|
LINKS
|
Eric Weisstein's World of Mathematics, Cograph
Index entries for sequences related to rooted trees
|
|
FORMULA
|
G.f.: A(x) = (B(x)^2+B(x^2))/2, where B(x) = g.f. for A000669. - Vladeta Jovovic (vladeta(AT)eunet.rs), May 07 2005
|
|
CROSSREFS
|
Cf. A106240.
Sequence in context: A109220 A018034 A000227 this_sequence A129429 A084204 A132364
Adjacent sequences: A058734 A058735 A058736 this_sequence A058738 A058739 A058740
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
N. J. A. Sloane (njas(AT)research.att.com), Jan 01 2001
|
|
EXTENSIONS
|
More terms from Vladeta Jovovic (vladeta(AT)eunet.rs), May 07 2005
|
|
|
Search completed in 0.002 seconds
|
