665665domain: NAppears in sequencesExpansion of e.g.f. tanh(exp(x)*x).at n=9A009768(prime(n))^3-(nonprime(n))^3 .at n=23A163121Irregular triangle M_2(n,k) read by rows: number of maximum k-matchings in rooted plane trees of size n, 1<=k<=n/2, 2<=n.at n=33A219731a(n) = Fibonacci(n+1)^3 - Fibonacci(n-1)^3.at n=10A350473