Thank you for your help. I wouldn't know for which command to look under Help.
Now I have the more difficult problem of including multiple if and then statements within my recursion. My recursion is
c[i+1,j,k,l] : = (1/((i+1)*d))* sum(iq*d[i+1-iq]*c[iq,j,k,l],iq=1..i) +
with c[i,j,k,l] = 0 if any of i,j,k,l <0,
c[0,j,k,l] = 0 for all j,k,l if k>0
c[i,0,k,l] = 0 for i,k,l if l>0
and c[0,j,0,l] are assumed known for all j,l and c[i,0,k,0] are assumed known for all i,k and the arrays d[ ] and e[ ] consist of algebraically independent indeterminates.
Hence, I seek to express c[i,j,k,l] in terms of c[0,j',0,l'], c[i',0,k',0], d,d,...etc e,e,e...etc