Number of (undirected) Hamiltonian paths in the n-ladder graph K_2 X P_n.

Terms

a(0) =1a(1) =4a(2) =8a(3) =14a(4) =22a(5) =32a(6) =44a(7) =58a(8) =74a(9) =92a(10) =112a(11) =134a(12) =158a(13) =184a(14) =212a(15) =242a(16) =274a(17) =308a(18) =344a(19) =382a(20) =422a(21) =464a(22) =508a(23) =554a(24) =602a(25) =652a(26) =704a(27) =758a(28) =814a(29) =872