login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A272109 Denominators of coefficients of the series of sqrt(-log(1-q)/q). 2
1, 4, 96, 384, 92160, 40960, 61931520, 49545216, 16986931200, 475634073600, 125567395430400, 7972533043200, 3656522554933248000, 195014536263106560, 70205233054718361600, 280820932218873446400, 4582997613812014645248000, 26453088680011628544000 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

The function sqrt(-log(1-q)/q) is associated with the generating function of connected graphs enumeration

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..200

P. Flajolet, B. Salvy, and G. Schaeffer, Airy Phenomena and Analytic Combinatorics of Connected Graphs, Electronic Journal of Combinatorics, Volume 11(1), 2004, Research Paper #R34 page 8.

MAPLE

gf := sqrt(-log(1-q)/q) ;

taylor(%, q=0, 18) ;

gfun[seriestolist](%) ;

map(denom, %) ; # R. J. Mathar, Mar 15 2018

MATHEMATICA

s = Sqrt[Log[1/(1 - q)]/q] + O[q]^20; CoefficientList[s, q] // Denominator

PROG

(PARI) Vec(apply(denominator, sqrt(-log(1-'q)/'q))) \\ M. F. Hasler, Mar 16 2018

CROSSREFS

Cf. A272108 (numerators).

Sequence in context: A302121 A188895 A068114 * A203316 A202682 A089639

Adjacent sequences:  A272106 A272107 A272108 * A272110 A272111 A272112

KEYWORD

nonn,frac

AUTHOR

Jean-Fran├žois Alcover, Apr 20 2016

EXTENSIONS

Definition corrected by Juan Arias-de-Reyna, Mar 15 2018

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.

License Agreements, Terms of Use, Privacy Policy. .

Last modified July 7 15:31 EDT 2020. Contains 335495 sequences. (Running on oeis4.)