OFFSET
0,2
COMMENTS
Triangle A104546(n,k) = the number of Schroeder paths of length 2n and having k platforms.
FORMULA
Self-convolution of A118927.
PROG
(PARI) {a(n)=local(G=1+x+x*O(x^n)); if(n==0, 1, for(i=0, n, G=1+x*G+x*G*(G+(y-1)*x/(1-x))); sum(k=0, n\2, a(k)*polcoeff(polcoeff(G+y*O(y^k), n, x), k, y)))}
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, May 06 2006
STATUS
approved