chapter  9
Sums of Type II(3,3,z)
Pages 1

Theorem 9.1 (Pfaff-Saalschu¨tz Formula). If a1 + a2 + b1 + b2 = n − 1, then

( n

k

) [a1]k [a2]k [b1]n−k [b2]n−k (−1)k = [a1 + b1]n [a1 + b2]n

= [b1 + a1]n [b1 + a2]n (−1)n. (9.1)

The quotient is

qps = (n− k) (a1 − k) (a2 − k)

(−1− k) (n− 1− b1 − k) (n− 1− b2 − k) .