Let p¯k(n) be the number of partitions of n with largest part at most k which is equivalent to partition into at most k parts. I do know an expression for that function. ( product of 1/1(1-n) through 1/(1-n)^k )
What I am searching for is an expression that gives that number of partitions under both restrictions, so all partitions of n that have at most k parts AND all parts <= j.