SOP and POS (noch nicht übersetzt)
Problem 851
Let n be a positive integer and let En be the set of n-tuples of strictly positive integers.
For u=(u1,⋯,un) and v=(v1,⋯,vn) two elements of En, we define:
- the Sum Of Products of u and v, denoted by ⟨u,v⟩, as the sum n∑i=1uivi;
- the Product Of Sums of u and v, denoted by u⋆v, as the product n∏i=1(ui+vi).
Let Rn(M) be the sum of u⋆v over all ordered pairs (u,v) in En such that ⟨u,v⟩=M.
For example: R1(10)=36, R2(100)=1873044, R2(100!)≡446575636mod109+7.
Find R6(10000!). Give your answer modulo 109+7.