509601domain: NAppears in sequencesNumber of length n+5 0..2 arrays with at most one downstep in every n consecutive neighbor pairs.at n=26A255112G.f. A(x) satisfies: 1 = Sum_{n>=0} x^n * ((1 + 2*x)^n - A(x))^(n+1), where A(0) = 0.at n=8A325582