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A140426
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Number of multi-symmetric Steinhaus matrices of size n.
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0
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1, 1, 2, 1, 2, 2, 2, 2, 4, 2, 4, 4, 4, 4, 8, 4, 8, 8, 8, 8, 16, 8, 16, 16, 16, 16, 32, 16, 32, 32, 32, 32, 64, 32, 64, 64, 64, 64, 128, 64, 128, 128, 128, 128, 256, 128, 256, 256, 256, 256, 512, 256, 512, 512, 512, 512, 1024, 512, 1024, 1024, 1024, 1024, 2048, 1024, 2048, 2048, 2048, 2048, 4096, 2048
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OFFSET
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0,3
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COMMENTS
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Theorem 3.7, p. 9, of Chappelon.
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LINKS
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FORMULA
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a(n) = 2^ceiling(n/6) for n even, 2^ceiling((n-3)/6) for n odd.
G.f.: ( -1-x-2*x^2-x^3-2*x^4-2*x^5 ) / ( -1+2*x^6 ). - R. J. Mathar, Jan 22 2011
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MATHEMATICA
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LinearRecurrence[{0, 0, 0, 0, 0, 2}, {1, 1, 2, 1, 2, 2}, 100] (* Jean-François Alcover, Sep 25 2019 *)
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PROG
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(PARI) Vec((1 + x + 2*x^2 + x^3 + 2*x^4 + 2*x^5)/(1 - 2*x^6) + O(x^80)) \\ Andrew Howroyd, Nov 03 2018
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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STATUS
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approved
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