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A078797 Sum of square displacements over all self-avoiding n-step walks on square lattice. Numerator of mean square displacement s(n)=a(n)/A046661(n). +0
4
1, 8, 41, 176, 679, 2452, 8447, 28120, 91147, 289324, 902721, 2777112, 8441319, 25398500, 75744301, 224156984, 658855781, 1924932324, 5593580859, 16175728584, 46572304083, 133556779740, 381611332725, 1086759598120 (list; graph; listen)
OFFSET

1,2

COMMENT

A comparison with the conjectured asymptotic behavior of the mean square displacement s(n) over all n-step self-avoiding walks given in E.Weissteins MathWorld article is shown in "Asymptotic Behavior of Mean Square Displacement" at first link

REFERENCES

See under A001411

LINKS

I. Jensen, Table of n, a(n) for n = 1..59 [from the Jensen link below]

I. Jensen, Series Expansions for Self-Avoiding Walks

Hugo Pfoertner, Results for the 2D Self-Trapping Random Walk

Eric Weisstein's World of Mathematics, Self-Avoiding Walk Connective Constant, Section from World of Mathematics

FORMULA

a(n)=sum k=1, A046661(n) ( i_k^2 + j_k^2 ) where (i_k, j_k) are the end points of all different self-avoiding n-step walks

EXAMPLE

Example: a(2)=8 because the A046661(2)=3 different self-avoiding 2-step walks end at (1,-1),(1,1)->d^2=2 and at (2,0)->d^2=4, so a(2) = 2*2 + 1*4 = 8 a(3)=41 because the end-points of the 9 different 3-step walks are: (0,-1),(0,1)->d^2=1, (1,-2),(1,2),(2,-1),(2,-1),(2,1),(2,1)->d^2=5, (3,0)->d^2=9. a(3) = 2*1 + 6*5 + 1*9 = 41 See also "Distribution of end point distance" at first link

PROGRAM

Source code of "FORTRAN program for distance counting" available at first link

CROSSREFS

Cf. A001411, A046661.

Sequence in context: A041116 A135797 A133106 this_sequence A156790 A080840 A026968

Adjacent sequences: A078794 A078795 A078796 this_sequence A078798 A078799 A078800

KEYWORD

frac,nonn

AUTHOR

Hugo Pfoertner (hugo(AT)pfoertner.org), Dec 05 2002

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Last modified December 17 19:39 EST 2009. Contains 170821 sequences.


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