OFFSET
0,1
COMMENTS
If Y is a 5-subset of an n-set X then, for n>=12, a(n-12) is the number of 8-subsets of X having at most one element in common with Y. > - Milan Janjic, Dec 08 2007
FORMULA
a(n)= (n+40)*binomial(n+7, 7)/8 = 5*b(n)-4*b(n-1), with b(n):=A000581(n+8)=binomial(n+8, 8).
G.f.: (5-4*x)/(1-x)^9.
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Wolfdieter Lang, Jul 16 2004
STATUS
approved