3720086

Appears in sequences

• a(n) = Sum_{k=0..2n} (k+1) * A027082(n, 2n-k).at n=13A027107
• a(n) = 7*9^n - 1.at n=6A198965
• Expansion of g.f.: (1 + x - 2*x^2 + 2*x^4)/((1-x)*(1-3*x^2)).at n=27A358027