Number of matchings in Moebius ladder M_n.

Terms

a(0) =10a(1) =34a(2) =106a(3) =344a(4) =1102a(5) =3546a(6) =11394a(7) =36628a(8) =117730a(9) =378426a(10) =1216378a(11) =3909832a(12) =12567446a(13) =40395794a(14) =129844994a(15) =417363332a(16) =1341539194a(17) =4312135922a(18) =13860583626a(19) =44552347608a(20) =143205490526a(21) =460308235562