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Search: id:A103333
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| A103333 |
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Number of closed walks on the graph of the (7,4) Hamming code. |
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+0
6
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| 1, 3, 24, 192, 1536, 12288, 98304, 786432, 6291456, 50331648, 402653184, 3221225472, 25769803776, 206158430208, 1649267441664, 13194139533312, 105553116266496, 844424930131968, 6755399441055744, 54043195528445952
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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Counts closed walks of length 2n at the degree 3 node of the graph of the (7,4) Hamming code. With interpolated zeros, counts paths of length n at this node.
Except the first term, numbers n such that n^2 = [A000302]^3 + [A004171]^3 [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Jan 22 2009]
a(n+1) = A157176(A016945(n)). [From Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Feb 24 2009]
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REFERENCES
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David J.C. Mackay, Information Theory, Inference and Learning Algorithms, CUP, 2003, p. 19
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FORMULA
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G.f.: (1-5x)/(1-8x); a(n)=(3*8^n+5*0^n)/8.
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CROSSREFS
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Cf. A082412, A103334.
Cf. A000302, A004171 [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Jan 22 2009]
Sequence in context: A027324 A122741 A136325 this_sequence A037762 A037650 A037769
Adjacent sequences: A103330 A103331 A103332 this_sequence A103334 A103335 A103336
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KEYWORD
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easy,nonn
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AUTHOR
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Paul Barry (pbarry(AT)wit.ie), Jan 31 2005
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