OFFSET
0,1
COMMENTS
If Y is a 5-subset of an n-set X then, for n>=10, a(n-10) is the number of 6-subsets of X having at most one element in common with Y. > - Milan Janjic, Dec 08 2007
FORMULA
G.f.: (5-4*x)/(1-x)^7.
a(n)= (n+30)*binomial(n+5, 5)/6 = 5*b(n)-4*b(n-1), with b(n):=A000579(n+6)=binomial(n+6, 6).
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Wolfdieter Lang, Jul 16 2004
STATUS
approved