Number of (undirected) cycles in the graph C_3 X P_n.

Terms

a(0) =1a(1) =14a(2) =63a(3) =220a(4) =701a(5) =2154a(6) =6523a(7) =19640a(8) =59001a(9) =177094a(10) =531383a(11) =1594260a(12) =4782901a(13) =14348834a(14) =43046643a(15) =129140080a(16) =387420401a(17) =1162261374a(18) =3486784303a(19) =10460353100a(20) =31381059501a(21) =94143178714a(22) =282429536363a(23) =847288609320