Number of perfect matchings (or domino tilings) in D_4 X P_(n-1).

Terms

a(0) =0a(1) =1a(2) =1a(3) =6a(4) =13a(5) =49a(6) =132a(7) =433a(8) =1261a(9) =3942a(10) =11809a(11) =36289a(12) =109824a(13) =335425a(14) =1018849a(15) =3104934a(16) =9443629a(17) =28756657a(18) =87504516a(19) =266383153a(20) =810723277a(21) =2467770054a(22) =7510988353a(23) =22861948801a(24) =69584925696a(25) =211799836801a(26) =644660351425