

A103334


Number of closed walks of length 2n at any of the nodes of degree 1 on the graph of the (7,4) Hamming code.


2



1, 1, 4, 24, 176, 1376, 10944, 87424, 699136, 5592576, 44739584, 357914624, 2863312896, 22906494976, 183251943424, 1466015514624, 11728124051456, 93824992280576, 750599937982464, 6004799503335424, 48038396025634816
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OFFSET

0,3


COMMENTS

a(n+1)=8^n/3+2^(n+1)/3 with g.f. (16x)/(110x+16x^2) counts walks of length 2n+1 between adjacent nodes of degrees 1 and 4 on the graph of the (7,4) Hamming code.


REFERENCES

David J.C. Mackay, Information Theory, Inference and Learning Algorithms, CUP, 2003, p. 19.


LINKS

Table of n, a(n) for n=0..20.
Index entries for linear recurrences with constant coefficients, signature (10,16).


FORMULA

G.f.: (19x+10x^2)/(110x+16x^2); a(n)=8^(n1)/3+2^(n)/3+5*0^n/8.


CROSSREFS

Cf. A082412, A103333.
Sequence in context: A221088 A032349 A215709 * A156017 A000309 A112914
Adjacent sequences: A103331 A103332 A103333 * A103335 A103336 A103337


KEYWORD

easy,nonn


AUTHOR

Paul Barry, Jan 31 2005


STATUS

approved



