2863267840domain: NAppears in sequencesNumber of walks of length n along the edges of an octahedron starting and ending at a vertex and also ( with a(0)=0 ) between two opposite vertices.at n=17A054881Decimal equivalents of A268229.at n=17A268230Numbers n such that sigma(n) - 1 and sigma(phi(n)) are both primes.at n=37A270416