399310

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=13A001998
• a(n) = (3^n+1)*(3^(n+1)+1)/4.at n=6A051405
• Number of connected unlabeled vertex-transitive graphs with n nodes such that complement is also connected.at n=44A054917