OFFSET
5,2
COMMENTS
Partial sums of number of diagonal dissections of a convex n-gon into n-4 regions. Partial sums of number of standard tableaux of shape (n-4,n-4,1,1). All values shown are nonprime.
FORMULA
a(n) = SUM[i=5..n] A002055(i) = SUM[i=5..n] binomial(i-3, 2)*binomial(2*i-6, i-5)/(i-4).
EXAMPLE
a(9) = 1 + 9 + 56 + 300 + 1485 = 1851 = 3 * 617.
CROSSREFS
KEYWORD
nonn
AUTHOR
Jonathan Vos Post, May 09 2010
STATUS
approved