150606

Appears in sequences

• Number of self-avoiding walks of length n on square lattice such that at each point the angle turns 90 degrees (the first turn is assumed to be to the left - otherwise the number must be doubled).at n=25A189722
• a(n) = Sum_{k=0..n} binomial(n,k) * A000108(k) * k^k.at n=5A349639