Number of (undirected) paths in the prism graph Y_n.

Terms

a(0) =1a(1) =26a(2) =129a(3) =444a(4) =1285a(5) =3366a(6) =8281a(7) =19544a(8) =44829a(9) =100770a(10) =223201a(11) =488916a(12) =1061749a(13) =2289854a(14) =4910505a(15) =10480176a(16) =22275661a(17) =47178234a(18) =99605809a(19) =209704940a(20) =440390181a(21) =922733526a(22) =1929364729a(23) =4026514824a(24) =8388588925a(25) =17448283346a(26) =36238762881a(27) =75161901444a(28) =155692535509a(29) =322122515310