5004720

Appears in sequences

• a(n) = permanent M_n where M_n is the n X n matrix m(i,j) = 2*i + j.at n=5A278927
• Triangle read by rows: T(n,m) (1<=m<=n) = number of surjections f:[n]->[m] with f(n) != f(j), j<n.at n=50A380977