-193710245

Appears in sequences

• a(1)=-1; a(2)=-1; a(3)=-2; a(n) = 4*a(n-1) - 3*a(n-2) for n >= 4.at n=19A123183
• a(n) = (-1)^(n+1) * (3^n+1)/2.at n=18A341463