OFFSET
0,3
COMMENTS
The square grid graph G_(3,3) has 9 vertices, 12 edges and 10 rectangles.
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..1000
Eric Weisstein's World of Mathematics, Grid Graph
FORMULA
a(n) = n*(n-1)^2*(n^6+2*n^5+3*n^4-6*n^3-15*n^2-4*n+12).
G.f.: 36 *x^2 *(x^7 +18*x^6 +481*x^5 +2280*x^4 +4355*x^3 +2594*x^2 +347*x+4) / (x-1)^10.
MAPLE
a:= n-> (((((n^3-10)*n^2+20)*n+5)*n-28)*n+12)*n:
seq(a(n), n=0..30);
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Alois P. Heinz, Dec 21 2014
STATUS
approved