Suppose we have the following equation:
g_ma_m=r_ma_{m-1}
with initial condition a_L=d and L might be negative.
The following command
RSolve[{g[m] a[m] == r[m] a[m - 1], a[-10] == d}, a, m]
gives me
{{a -> Function[{m},
d*Product[r[1 + K[1]]/g[1 + K[1]], {K[1], 0, -1 + m}]]
}}
where K[1] runs from 0 to m-1. But shouldn’t K[1] runs from -10 to m-1?