

A135443


Number of maximal directed trails in the labeled nladder graph P_2 X P_n.


0



2, 8, 12, 40, 84, 144, 220, 312, 420, 544, 684, 840, 1012, 1200, 1404, 1624, 1860, 2112, 2380, 2664, 2964, 3280, 3612, 3960, 4324, 4704, 5100, 5512, 5940, 6384, 6844, 7320, 7812, 8320, 8844, 9384, 9940, 10512, 11100, 11704, 12324, 12960, 13612, 14280
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OFFSET

1,1


LINKS



FORMULA



EXAMPLE

For n = 4 the graph is
.__.__.__.
______
Names of nodes:
1 2 3 4
a b c d
Maximal directed paths which start from node 3:
34dcba123c
34dc32ba12
34dc321ab2
34dc321abc
3cd432ba12
3cd4321ab2
3cd4321abc
3cba1234dc
321abc34dc
321abcd43c
There are also paths from nodes c,b,2. So n(4) = 4*10 = 40.


CROSSREFS

Apart from initial terms sequence is the same as A033586.


KEYWORD

nonn,walk


AUTHOR



EXTENSIONS



STATUS

approved



