Number of perfect matchings in graph P_{6} X P_{n}.

Terms

a(0) =1a(1) =1a(2) =13a(3) =41a(4) =281a(5) =1183a(6) =6728a(7) =31529a(8) =167089a(9) =817991a(10) =4213133a(11) =21001799a(12) =106912793a(13) =536948224a(14) =2720246633a(15) =13704300553a(16) =69289288909a(17) =349519610713