OFFSET
0,8
COMMENTS
FORMULA
a(n, m)=0 if n<m; a(0, 0)=1, a(n, 0)=0 if n >= 1; a(n, m)= a(n-1, m)+sum(a(k, m-1), k=m-1..n-1) if n+m even and a(n, m)= a(n-1, m)+sum(a(k, m-1), k=m-1..n-1)-binomial((n+m-3)/2, m-1) if n+m odd, n >= m >= 1.
EXAMPLE
{1}; {0,1}; {0,1,1}; {0,2,2,1}; ...; Pe(4,x^2)=1+6*x^2+x^4.
CROSSREFS
KEYWORD
AUTHOR
Wolfdieter Lang, Jun 19 2001
STATUS
approved