170667

Appears in sequences

• a(0) = 0, a(1) = 1; for n>0, a(2*n) = 3*a(2*n-1), a(2*n+1) = 3*a(2*n) - 2*a(n-1).at n=12A129770
• a(0) = 1, a(1) = 2; for n>0, a(2*n) = 3*a(2*n-1) - a(2*n-2), a(2*n+1) = 3*a(2*n) - a(2*n-1) - a(n-1).at n=13A129804
• Indices of the pentagonal numbers listed in A209049.at n=21A209048
• The Wiener index of the linear phenylene with n hexagons.at n=20A224454