#251comb    Computes C(n, r) from n and r in C1
let k1 = c1(1)
let k2 = c1(2)
name k1 'n'
name k2 'r'
let k3 = 1
let k4 = k1
let k5 = k2
execute '251fract' k2
name k3 'c'
print k1-k3
end