Number of total dominating sets in the n-barbell graph.

Terms

a(0) =1a(1) =4a(2) =23a(3) =136a(4) =707a(5) =3312a(6) =14527a(7) =61264a(8) =252515a(9) =1027192a(10) =4147343a(11) =16674984a(12) =66887875a(13) =267960544a(14) =1072726271a(15) =4292804896a(16) =17175281987a(17) =68709777768a(18) =274857460111