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A038579 Number of self-avoiding closed walks from 0 of area n in strip Z X {0,1,2}. 0
1, 4, 10, 28, 64, 140, 304, 640, 1326, 2716, 5502, 11052, 22044, 43700, 86180, 169184, 330810, 644564, 1251954, 2424860, 4684696, 9029756, 17368408, 33343520, 63899686, 122259372, 233568998, 445600236, 849014964, 1615709156, 3071307852 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

REFERENCES

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

LINKS

Table of n, a(n) for n=0..30.

FORMULA

G.f.= 2(1+2x^3+2x^4)/(1-x-x^2-x^3)^2-1 [Labelle] - Emeric Deutsch, Apr 29 2004

MATHEMATICA

CoefficientList[ Series[(2 + 4 x^3 + 4 x^4)/(1 - x - x^2 - x^3)^2 - 1, {x, 0, 28}], x]

CROSSREFS

Cf. A022445, A038578.

Sequence in context: A174938 A032248 A092504 * A133726 A026534 A034920

Adjacent sequences:  A038576 A038577 A038578 * A038580 A038581 A038582

KEYWORD

nonn,walk,easy

AUTHOR

N. J. A. Sloane.

EXTENSIONS

More terms from Emeric Deutsch, Apr 29 2004

STATUS

approved

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Last modified December 11 07:18 EST 2019. Contains 329914 sequences. (Running on oeis4.)