login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A079479 Denominator of number J(n) arising in computation of second moment of A*_n lattice. 1
1, 12, 18, 32, 375, 648, 33614, 196608, 1594323, 625000, 14147686146, 35831808, 1792160394037, 94911683664, 1922167968750, 140737488355328, 8587269154529447379, 61004779879896, 10960773715569604371878, 384000000000000000, 123629392983875275287, 978545447174632740656 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

REFERENCES

J. H. Conway and N. J. A. Sloane, "Sphere Packings, Lattices and Groups", Springer-Verlag, p. 476.

LINKS

Table of n, a(n) for n=1..22.

EXAMPLE

0, 1/12, 5/18, 19/32, 389/375, 1045/648, 78077/33614, ...

MAPLE

J := proc(n) option remember; local i; if n <= 1 then 0 else (n!/(8*(n+1)*n^(n-2))) * add( n^k/k!, k=0..n) -n^2/(4*(n+1)) +(1/(n+1))*add( binomial(n, i)*(i/n)^i*( (n-i)/n)^(n-i-1)*J(i), i=1..n-1); fi; end;

CROSSREFS

Cf. A072526.

Sequence in context: A007371 A277725 A319746 * A293692 A162694 A230354

Adjacent sequences:  A079476 A079477 A079478 * A079480 A079481 A079482

KEYWORD

nonn,frac

AUTHOR

N. J. A. Sloane, Aug 02 2003

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 March 18 19:58 EDT 2019. Contains 321293 sequences. (Running on oeis4.)