Number of maximal directed trails in the labeled n-ladder graph P_2 X P_n.

Terms

a(0) =2a(1) =8a(2) =12a(3) =40a(4) =84a(5) =144a(6) =220a(7) =312a(8) =420a(9) =544a(10) =684a(11) =840a(12) =1012a(13) =1200a(14) =1404a(15) =1624a(16) =1860a(17) =2112a(18) =2380a(19) =2664a(20) =2964a(21) =3280a(22) =3612a(23) =3960a(24) =4324a(25) =4704a(26) =5100a(27) =5512a(28) =5940a(29) =6384