A072526 - OEIS

A072526

Numerator of number J(n) arising in computation of second moment of A*_n lattice.

0, 1, 5, 19, 389, 1045, 78077, 623245, 6626426, 3301971, 92695530505, 285361879, 17061288862565, 1065000744223, 25118392969537, 2119645764556535, 147712619442026368532, 1188946883458975, 240322519506608309910831, 9412105864959423959, 3368266474732313495945, 29482240157146090479193

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,3

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. A079479.

Sequence in context: A122150 A368888 A092663 * A095218 A119964 A270477

Adjacent sequences: A072523 A072524 A072525 * A072527 A072528 A072529

KEYWORD

nonn,frac

AUTHOR

N. J. A. Sloane, Aug 02 2003

STATUS

approved