OFFSET
1,1
COMMENTS
The Wiener index of a connected graph is the sum of distances between all unordered pairs of vertices in the graph.
The Wiener polynomial of D(m,n) is (1/2)n(m-1)t[(m-1)(n-1)t+m].
The Wiener index of D(m,n) is (1/2)n(m-1)[(m-1)(2n-1)+1].
LINKS
B. E. Sagan, Y-N. Yeh and P. Zhang, The Wiener Polynomial of a Graph, Internat. J. of Quantum Chem., 60, 1996, 959-969.
Eric Weisstein's World of Mathematics, Windmill Graph.
Index entries for linear recurrences with constant coefficients, signature (3,-3,1).
FORMULA
a(n) = 5n(5n-2).
G.f.: -5*x*(7*x+3)/(x-1)^3. - Colin Barker, Oct 30 2012
MAPLE
seq(5*n*(-2+5*n), n = 1 .. 40);
PROG
(PARI) a(n)=5*n*(5*n-2) \\ Charles R Greathouse IV, Jun 17 2017
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Emeric Deutsch, Sep 21 2010
STATUS
approved