Total number of distinct solutions (modulo lcm(1,2,...,n)) of the system of congruences x == i (mod p(i)), i=1,2,...,n, where p is a permutation of order n.
The system of congruences x == i (mod p(i)) has the same solution as the system of congruences x == n-1-i (mod p'(i)) where p'=(p(n),p(n-1),...,p(1)). Therefore this sequence also gives the number of distinct solutions to the system of congruences x == -i (mod p(i)), i=1,2,...,n.
