OFFSET
1,1
COMMENTS
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.
FORMULA
T(n,1)=3n; T(n,k) = 4(n-k+1) for k>1.
G.f. = G(q,z) = qz/(3+qz)/((1-qz)*(1-z)^2).
EXAMPLE
T(2,1)=6 because the chain of 2 triangles has 6 edges.
Triangle starts:
3;
6, 4;
9, 8, 4;
12, 12, 8, 4;
15, 16, 12, 8, 4;
MAPLE
T:=proc(n, k) if n < k then 0 elif k = 1 then 3*n else 4*n-4*k+4 end if end proc: for n to 12 do seq(T(n, k), k=1..n) end do; # yields sequence in triangular form
CROSSREFS
KEYWORD
nonn,tabl
AUTHOR
Emeric Deutsch, Sep 06 2008
STATUS
approved