This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A003163 Denominators of Van der Pol numbers. (Formerly M1534) 2
 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; refs; listen; history; text; internal format)
 OFFSET 0,2 REFERENCES N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). LINKS T. D. Noe, Table of n, a(n) for n=0..200 F. T. Howard, Properties of the van der Pol numbers and polynomials, R. Reine Angew. Math., 260 (1973), 35-46. FORMULA E.g.f.: x^3/( 6*x*(exp(x)+1)-12*(exp(x)-1) ). EXAMPLE 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 MAPLE 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); # Emeric Deutsch, Dec 23 2004 MATHEMATICA max = 26; g[x_] = x^3/(6*x*(E^x + 1) - 12*(E^x - 1)); Denominator[ CoefficientList[ Series[ g[x], {x, 0, max}], x]*Range[0, max]!](* Jean-François Alcover, Nov 17 2011, after g.f. *) CROSSREFS Cf. A003164. Sequence in context: A308522 A216462 A006893 * A088498 A240147 A293687 Adjacent sequences:  A003160 A003161 A003162 * A003164 A003165 A003166 KEYWORD nonn,frac,nice,easy AUTHOR EXTENSIONS More terms from Emeric Deutsch, Dec 23 2004 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified October 16 13:51 EDT 2019. Contains 328093 sequences. (Running on oeis4.)