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.

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

Offset

0,3

Comments

a(n+1)=8^n/3+2^(n+1)/3 with g.f. (1-6x)/(1-10x+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.: (1-9x+10x^2)/(1-10x+16x^2); a(n)=8^(n-1)/3+2^(n)/3+5*0^n/8.

Crossrefs

Cf. A082412, A103333.

Sequence in context: A347651 A032349 A215709 * A156017 A000309 A112914

Adjacent sequences: A103331 A103332 A103333 * A103335 A103336 A103337

Keyword

easy,nonn

Author

Paul Barry, Jan 31 2005

Status

approved