1197504domain: 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=17A054026a(n) = n^4*binomial(2*n,n).at n=6A069121