81015

Appears in sequences

• Dirichlet g.f.: Product_{k>=2} 1 / (1 - k^(-s))^binomial(k+3,4).at n=29A344204
• For 1<=x<=n, 1<=y<=n, with gcd(x,y)=1, write 1 = gcd(x,y) = u*x+v*y with u,v minimal; a(n) = sum of the values of u^2+v^2.at n=38A345431
• Array read by antidiagonals: T(n,k) is the number of nonisomorphic multisets of fixed-point-free endofunctions on an n-set with k endofunctions.at n=40A362899
• Number of nonisomorphic multisets of fixed-point-free endofunctions on an n-set with n endofunctions.at n=4A362902