OFFSET
3,2
LINKS
Alois P. Heinz, Table of n, a(n) for n = 3..1000
Wikipedia, Partition of a set
FORMULA
G.f.: -(1/2)*(3*x-1+sqrt((1-3*x)*(x+1)*(2*x-1)^2))/((3*x-1)*(x+1)).
a(n) ~ 3^(n-1/2) / (4*sqrt(Pi*n)). - Vaclav Kotesovec, Aug 02 2016
Recurrence: (n-3)*n*a(n) = (n^2 - 3*n + 4)*a(n-1) + (n-2)*(5*n - 11)*a(n-2) + 3*(n-3)*(n-2)*a(n-3). - Vaclav Kotesovec, Aug 02 2016
CROSSREFS
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Jul 22 2016
STATUS
approved