1592865

Appears in sequences

• a(1) = a(2) = 1, a(3) = 9; for n > 3, a(n) = 3*a(n-1) - 3*a(n-2) + 9*a(n-3).at n=13A101990
• Sum 3^max(k,n-k),k=0..n.at n=12A107660
• Inverse binomial transform of (A113405 preceded by 0).at n=15A133474