

A063888


Number of nstep walks on a cube lattice starting from the origin but not returning to it at any stage.


0



1, 6, 30, 180, 1026, 6156, 35940, 215640, 1271106, 7626636, 45182124, 271092744, 1610875836, 9665255016, 57546367704, 345278206224, 2058613385346, 12351680312076, 73717606430364, 442305638582184, 2641804748619732
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OFFSET

0,2


COMMENTS

a(n)/6^n tends to 0.65946...


REFERENCES

Steven R. Finch, Mathematical Constants, Cambridge, 2003, pp. 322331.


LINKS



FORMULA

a(2n) = 6*a(2n1)A049037(n); a(2n+1) = 6*a(2n).


EXAMPLE

a(2) = 30 since there are 36 2step walks but 6 of them involve a return to the origin at some stage; similarly a(3) = 180 since there are 216 3step walks but 36 of them involve a return to the origin at some stage.


CROSSREFS



KEYWORD

nonn


AUTHOR



STATUS

approved



