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Search: id:A005327
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| A005327 |
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Certain subgraphs of a directed graph (inverse binomial transform of A005321).
(Formerly M4289)
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+0
4
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| 1, 0, 1, 6, 91, 2820, 177661, 22562946, 5753551231, 2940064679040, 3007686166657921, 6156733583148764286, 25211824022994189751171
(list; graph; listen)
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OFFSET
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1,4
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REFERENCES
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Andresen, E.; Kjeldsen, K.; On certain subgraphs of a complete transitively directed graph. Discrete Math. 14 (1976), no. 2, 103-119.
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LINKS
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N. J. A. Sloane, Transforms
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FORMULA
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a(n)=p(n-1)*sum((-1)^j/p(j), j=0..n-1), 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
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MAPLE
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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/p(j), j=0..n-1): seq(a(n), n=1..17); (Deutsch)
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CROSSREFS
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Cf. A002820.
Adjacent sequences: A005324 A005325 A005326 this_sequence A005328 A005329 A005330
Sequence in context: A013297 A095864 A006151 this_sequence A113266 A053512 A009607
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KEYWORD
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nonn
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AUTHOR
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njas
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