193589270domain: NAppears in sequencesNumber of undirected walks of length n+1 on tetrahedron, visiting n+2 vertices, with n "corners", as in A001998, but allowing only rigid motions in 3-space (|G| = 12). Walks are not self-avoiding.at n=18A051436G.f. A(x) satisfies A(x) = 1 / (1 - x - x * (1 + x + x^2 + x^3) * A(x^4)).at n=20A367657