|
| |
|
|
A006059
|
|
Number of connected labeled T_0-T_4-topologies with n points.
(Formerly M1948)
|
|
9
|
|
|
|
1, 1, 2, 9, 76, 1095, 25386, 910161, 49038872, 3885510411, 445110425110, 72721717736613, 16755380125270788, 5393244363726095487, 2405910197342218830914, 1477264863856923105482745, 1241074736327051013648799024, 1419169006353332682835352361843
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
0,3
|
|
|
REFERENCES
|
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
|
|
|
LINKS
|
Herman Jamke, Table of n, a(n) for n = 0..19
M. Erné, Struktur- und Anzahlformeln für Topologien auf Endlichen Mengen, Manuscripta Math., 11 (1974), 221-259.
M. Erné, Struktur- und Anzahlformeln für Topologien auf Endlichen Mengen, Manuscripta Math., 11 (1974), 221-259. (Annotated scanned copy)
|
|
|
FORMULA
|
a(n) = n*A001035(n-1) for n>=1. - Herman Jamke (hermanjamke(AT)fastmail.fm), Mar 02 2008
|
|
|
MATHEMATICA
|
A001035 = Cases[Import["https://oeis.org/A001035/b001035.txt", "Table"], {_, _}][[All, 2]];
a[n_] := If[n == 0, 1, n A001035[[n]]];
a /@ Range[0, Length[A001035]] (* Jean-François Alcover, Dec 30 2019 *)
|
|
|
CROSSREFS
|
Sequences in the Erné (1974) paper: A000798, A001035, A006056, A006057, A001929, A001927, A006058, A006059, A000110.
Sequence in context: A132621 A108992 A058164 * A277406 A182947 A006041
Adjacent sequences: A006056 A006057 A006058 * A006060 A006061 A006062
|
|
|
KEYWORD
|
nonn,nice
|
|
|
AUTHOR
|
N. J. A. Sloane
|
|
|
EXTENSIONS
|
More terms from Detlef Pauly (dettodet(AT)yahoo.de), Dec 27 2001
|
|
|
STATUS
|
approved
|
| |
|
|
