204540

Appears in sequences

• Initial seeds x which will enter a cycle of length 4 under the iteration of x -> A063919(x), the sum of proper unitary divisors.at n=13A098187
• Triangle read by rows: a(1,1)=1. a(m,n) = a(m-1,n) + (sum of all terms in row m-1), for n<m. a(m,m) = sum of all terms in row m-1.at n=40A159930
• Triangle read by rows: The number of chord diagrams with n chords and k topologically connected components, 0 <= k <= n.at n=40A322402