|
| |
|
|
A005328
|
|
Certain subgraphs of a directed graph.
(Formerly M3118)
|
|
0
| |
|
|
1, 3, 28, 510, 18631, 1351413, 194192398, 55272612720, 31184369778961, 34909296450535023, 77616063417393956368, 343049603717222441078130, 3016429354620114423122804491, 52801416275268069417410827891833
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 2,2
|
|
|
REFERENCES
| Andresen, E.; Kjeldsen, K.; On certain subgraphs of a complete transitively directed graph. Discrete Math. 14 (1976), no. 2, 103-119.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
|
|
|
FORMULA
| a(n)=p(n-1)*sum((-1)^j*(n-1-j)/p(j), j=0..n-2), where p(0)=1, p(k)=product(2^i-1, i=1..k) for k>0. - Emeric Deutsch (deutsch(AT)duke.poly.edu), Jan 23 2005
|
|
|
MAPLE
| p:=proc(n) if n=0 then 1 else product(2^i-1, i=1..n) fi end: a:=n->p(n-1)*sum((-1)^j*(n-1-j)/p(j), j=0..n-2): seq(a(n), n=2..17); (Deutsch)
|
|
|
CROSSREFS
| Sequence in context: A108288 A058804 A180710 * A192559 A161971 A156315
Adjacent sequences: A005325 A005326 A005327 * A005329 A005330 A005331
|
|
|
KEYWORD
| nonn
|
|
|
AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
|
|
|
EXTENSIONS
| More terms from Emeric Deutsch (deutsch(AT)duke.poly.edu), Jan 23 2005
|
| |
|
|
