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A038577 Number of self-avoiding walks of length n from origin in strip Z X {0,1}. +0
2
1, 3, 6, 12, 20, 36, 58, 100, 160, 268, 430, 708, 1140, 1860, 3002, 4876, 7880, 12772, 20654, 33444, 54100, 87564, 141666, 229252, 370920, 600196, 971118, 1571340, 2542460, 4113828, 6656290, 10770148 (list; graph; listen)
OFFSET

0,2

COMMENT

For n>=2, a(n) coincides with A110935. [From Eric S Rowland (erowland(AT)math.rutgers.edu), Mar 09 2009]

REFERENCES

J. Labelle, Self-avoiding walks and polyominoes in strips, Bull. ICA, 23 (1998), 88-98.

LINKS

D. Zeilberger, [math/9506214] Self avoiding walks, the language of science and Fibonacci numbers

FORMULA

G.f.: (1+2*t-t^3-t^4+t^7)/(1-t)^2/(1+t)^2/(1-t-t^2).

MAPLE

f := n->if n mod 2 = 0 then 8*fibonacci(n)-n else 8*fibonacci(n)-4; fi;

CROSSREFS

Sequence in context: A006128 A079983 A028926 this_sequence A028925 A028924 A034738

Adjacent sequences: A038574 A038575 A038576 this_sequence A038578 A038579 A038580

KEYWORD

nonn,walk,easy

AUTHOR

N. J. A. Sloane (njas(AT)research.att.com).

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Last modified November 24 23:16 EST 2009. Contains 167481 sequences.


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