201642

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=10A098187
• The number of 123-avoiding simple involutions of length n.at n=27A230557
• Number of Dyck paths of semilength n avoiding the consecutive steps UDUUUDDDUD (with U=(1,1), D=(1,-1)).at n=12A243870
• Number T(n,k) of Dyck paths of semilength n having exactly k (possibly overlapping) occurrences of the consecutive steps UDUUUDDDUD (with U=(1,1), D=(1,-1)); triangle T(n,k), n>=0, 0<=k<=max(0,floor((n-1)/4)), read by rows.at n=22A243881
• E.g.f. A(x) satisfies A(x) = 1 + x^2*exp(x)*A(x)^3.at n=7A390647