8744736domain: NAppears in sequencesa(n) is the number of sets of natural numbers [a,b,c,d,e] that can be produced with the numbers [0..n] such that the values of all the distinct parenthesized expressions of a-b-c-d-e are different.at n=25A054026a(n) = binomial(n+5, 5) * binomial(n+7, 5).at n=9A107396