871725625

Appears in sequences

• Bending a piece of wire of length n+1; walks of length n+1 on a tetrahedron; also non-branched catafusenes with n+2 condensed hexagons.at n=20A001998
• a(n) = (3^n + 1)^2/4.at n=10A051500
• a(n) = (A046717(n))^2 (starting with n=1).at n=9A120096
• Number of 2 X n arrays of occupancy after each element moves to some horizontal, diagonal or antidiagonal neighbor, with every occupancy equal to zero or two.at n=19A221276