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A052178
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Number of walks of length n on the simple cubic lattice terminating at height 2 above the (x,y)-plane.
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1
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1, 12, 99, 700, 4569, 28476, 172508, 1026288, 6033690, 35195512, 204232809, 1181052756, 6814746393, 39267916380, 226097749224, 1301403695520, 7490649175326, 43123589230824, 248351880642630, 1430956006648056, 8249467230853002, 47587180659332248
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OFFSET
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2,2
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LINKS
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MAPLE
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b:= proc(n, k) option remember; `if`(min(n, k)<0, 0,
`if`(max(n, k)=0, 1, b(n-1, k-1)+4*b(n-1, k)+b(n-1, k+1)))
end:
a:= n-> b(n, 2):
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CROSSREFS
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KEYWORD
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nonn,walk
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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