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%I #8 Apr 19 2019 09:30:21
%S 1,6,30,180,1026,6156,35940,215640,1271106,7626636,45182124,271092744,
%T 1610875836,9665255016,57546367704,345278206224,2058613385346,
%U 12351680312076,73717606430364,442305638582184,2641804748619732
%N Number of n-step walks on a cube lattice starting from the origin but not returning to it at any stage.
%C a(n)/6^n tends to 0.65946...
%D Steven R. Finch, Mathematical Constants, Cambridge, 2003, pp. 322-331.
%H Steven R. Finch, <a href="http://www.people.fas.harvard.edu/~sfinch/constant/polya/polya.html">Polya's Random Walk Constants</a> [Broken link]
%H Steven R. Finch, <a href="http://web.archive.org/web/20010603070928/http://www.mathsoft.com/asolve/constant/polya/polya.html">Polya's Random Walk Constants</a> [From the Wayback machine]
%F a(2n) = 6*a(2n-1)-A049037(n); a(2n+1) = 6*a(2n).
%e a(2) = 30 since there are 36 2-step walks but 6 of them involve a return to the origin at some stage; similarly a(3) = 180 since there are 216 3-step walks but 36 of them involve a return to the origin at some stage.
%K nonn
%O 0,2
%A _Henry Bottomley_, Aug 28 2001
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