Number of vertex cuts in the n-ladder graph P_2 x P_n.

Terms

a(0) =0a(1) =2a(2) =23a(3) =147a(4) =748a(5) =3414a(6) =14719a(7) =61495a(8) =252364a(9) =1024938a(10) =4137207a(11) =16639339a(12) =66775964a(13) =267631726a(14) =1071801407a(15) =4290282671a(16) =17168559452a(17) =68692172578a(18) =274811988823