OFFSET
1,1
LINKS
J. Grassberger, A. King, P. Tirao, On the homology of free 2-step nilpotent Lie algebras, J. Algebra 254 (2002), 213-225.
FORMULA
a(n) = 2^ceiling(n/2)*f(floor((n-1)/2))*f(floor(n/2)), where f(n)= Product_{i=1..n} (4*i)!*i!^2/((2*i)!)^3.
a(n) ~ K*2^(n^2/2)*n^(1/8), where K=1.3814... - Nordine Fahssi, Jan 17 2019
From Jon E. Schoenfield, Jan 17 2019: (Start)
K = 1.38143139396100192327615434710888289668811010590733/
41912628937302462176044631403587011199108546012939...
(End)
MAPLE
f := proc(n) local i: mul((4*i)!*i!^2/((2*i)!)^3, i=1..n): end:seq(2^ceil(n/2)*f(floor((n-1)/2))*f(floor(n/2)), n=1..20);
CROSSREFS
KEYWORD
nonn
AUTHOR
Antonio G. Astudillo (afg_astudillo(AT)hotmail.com), Jan 12 2003
STATUS
approved