1956246

Appears in sequences

• Number of perfect matchings in the twisted graph (C_4 X C_n)_{(13)(24)}.at n=10A220868
• a(n) is the number of perfect matchings of an edge-labeled 2 X n Klein bottle grid graph, or equivalently the number of domino tilings of a 2 X n Klein bottle grid. (The twist is on the length-n side.)at n=21A351635