431739

Appears in sequences

• Number of rooted toroidal maps with 4 vertices and n faces and no isthmuses.at n=3A006427
• a(1)=1. Thereafter, a(n) = n*a(n-1) if the number of divisors of n*a(n-1) is <= the number of divisors of n+a(n-1) or a(n) = n+a(n-1) if n*a(n-1) has more divisors than n+a(n-1).at n=20A134189
• Triangle read by rows: T(n,k) is the number of rooted toroidal maps with n edges and k faces and without isthmuses, n >= 2, k = 1..n-1.at n=24A343092