1418981392

Appears in sequences

• Number of perfect matchings in the graph C_4 X C_n.at n=13A220864
• a(n) = 6 + 4*(-1)^n + (2+sqrt(3))^n + (2-sqrt(3))^n + 2*(1+sqrt(2))^n + 2*(1-sqrt(2))^n.at n=16A232999