Number of self-avoiding closed walks from 0 of area n in strip Z X {-1,0,1}.

Terms

a(0) =1a(1) =8a(2) =16a(3) =40a(4) =88a(5) =184a(6) =388a(7) =800a(8) =1628a(9) =3288a(10) =6584a(11) =13096a(12) =25904a(13) =50984a(14) =99916a(15) =195072a(16) =379572a(17) =736360a(18) =1424672a(19) =2749672a(20) =5295240a(21) =10176856a(22) =19522644a(23) =37387424a(24) =71487756a(25) =136492216a(26) =260255304a(27) =495618408a(28) =942731360a(29) =1791241544