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Search: id:A000270
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| A000270 |
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Number of discordant permutations.
(Formerly M3019 N1221)
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+0
1
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| 1, 1, 0, 3, 16, 95, 672, 5397, 48704, 487917, 5373920, 64547175, 839703696, 11762247419, 176509466560, 2825125339305, 48040633506048, 864932233294681, 16436901752820288, 328791893988472843, 6905593482159150480
(list; graph; listen)
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OFFSET
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0,4
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REFERENCES
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N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
J. Touchard, Permutations discordant with two given permutations, Scripta Math., 19 (1953), 109-119.
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FORMULA
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G.f.: G.f.: 1+(1-x)/(1+x)*Sum_{n>=0} n*n!*(x/(1+x)^2)^n. - Vladeta Jovovic (vladeta(AT)eunet.rs), Jun 29 2007
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MAPLE
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a:= n-> coeftayl (1+ (1-x)/(1+x) *add (k*k! *(x/ (1+x)^2)^k, k=0..n), x=0, n): seq (a(n), n=0..25); [From Alois P. Heinz (heinz(AT)hs-heilbronn.de), Sep 24 2008]
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CROSSREFS
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Sequence in context: A137644 A114174 A006347 this_sequence A157051 A000271 A157016
Adjacent sequences: A000267 A000268 A000269 this_sequence A000271 A000272 A000273
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KEYWORD
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nonn,nice
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
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More terms from Alois P. Heinz (heinz(AT)hs-heilbronn.de), Sep 24 2008
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