12643492

Appears in sequences

• a(2n) = a(2n-1) + 3a(2n-2), a(2n+1) = 2a(2n) + 3a(2n-1).at n=18A002537
• a(n) = ((4 + sqrt(7))^n + (4 - sqrt(7))^n)/2.at n=9A146964