4194366domain: NAppears in sequencesa(n) = 2^(n+1) - 1 + 3*n.at n=21A131833Number of (n+1) X (5+1) 0..1 arrays with nondecreasing x(i,j)-x(i,j-1) in the i direction and nonincreasing x(i,j)-x(i-1,j) in the j direction.at n=20A250739a(n) = Sum_{k=1..n} phi(gcd(k, n))^(gcd(k, n) - 1).at n=11A342544