OFFSET
0,1
COMMENTS
If Y is a 3-subset of an n-set X then, for n>=10, a(n-10) is the number of 8-subsets of X having at most one element in common with Y. - Milan Janjic, Nov 23 2007
FORMULA
a(n)= binomial(n+7, 7)*(n+24)/8 = 3*b(n)-2*b(n-1), with b(n):=binomial(n+8, 8); cf. A000581.
G.f.: (3-2*x)/(1-x)^9.
PROG
(PARI) x='x+O('x^66); Vec((3-2*x)/(1-x)^9) \\ Joerg Arndt, May 11 2013
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Wolfdieter Lang, Jun 11 2004
STATUS
approved