Number of matchings in graph P_{3} X P_{n}.

Terms

a(0) =1a(1) =3a(2) =22a(3) =131a(4) =823a(5) =5096a(6) =31687a(7) =196785a(8) =1222550a(9) =7594361a(10) =47177097a(11) =293066688a(12) =1820552297a(13) =11309395995a(14) =70254767718a(15) =436427542283