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Search: id:A003163
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| A003163 |
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Denominators of Van der Pol numbers.
(Formerly M1534)
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+0
2
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| 1, 2, 5, 20, 350, 140, 1050, 300, 57750, 38500, 250250, 45500, 2388750, 367500, 318750, 42500, 1088106250, 128012500, 960093750, 101062500, 105761906250, 10072562500, 2289218750, 199062500, 8842968750, 707437500, 51289218750
(list; graph; listen)
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OFFSET
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0,2
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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).
F. T. Howard, Properties of the van der Pol numbers and polynomials, R. Reine Angew. Math., 260 (1973), 35-46.
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LINKS
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T. D. Noe, Table of n, a(n) for n=0..200
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FORMULA
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E.g.f.: x^3/( 6*x*(exp(x)+1)-12*(exp(x)-1) ).
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EXAMPLE
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1, -1/2, 1/5, -1/20, -1/350, 1/140, 1/1050, -1/300, -37/57750, 111/38500, 177/250250, -177/45500, ... = A003163/A003164
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MAPLE
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G:=x^3/(6*x*(exp(x)+1)-12*(exp(x)-1)):Gser:=series(G, x=0, 35):1, seq(denom(n!*coeff(Gser, x^n)), n=1..31); (Deutsch)
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CROSSREFS
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Cf. A003164.
Sequence in context: A005331 A158872 A006893 this_sequence A088498 A039777 A000941
Adjacent sequences: A003160 A003161 A003162 this_sequence A003164 A003165 A003166
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KEYWORD
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nonn,frac,nice,easy
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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 Emeric Deutsch (deutsch(AT)duke.poly.edu), Dec 23 2004
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