OFFSET
2,1
LINKS
Lars Blomberg, Table of n, a(n) for n = 2..101
Andrei Asinowski, Christian Krattenthaler, Toufik Mansour, Counting triangulations of some classes of subdivided convex polygons, arXiv:1604.02870 [math.CO], 2016.
FORMULA
From Asinowski and Krattenthaler equation 2.7: a(n) = tr(n,4). - Lars Blomberg, Mar 04 2017
MATHEMATICA
tr[k_, r_] := Sum[(-1)^j 2^l Binomial[k, j] Binomial[k-2+l, l] Binomial[(r-1)k-l-3, r k - (r+1)j - l - 2], {j, 0, k}, {l, 0, r k - (r+1)j - 2}];
a[n_] := tr[n, 4];
Table[a[n], {n, 2, 16}] (* Jean-François Alcover, Oct 10 2018 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Mar 03 2017
EXTENSIONS
More terms from Lars Blomberg, Mar 04 2017
STATUS
approved