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A140426 Number of multi-symmetric Steinhaus matrices of size n. 0
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 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,3
COMMENTS
Theorem 3.7, p. 9, of Chappelon.
LINKS
Jonathan Chappelon, Regular Steinhaus graphs of odd degree, arXiv:0806.2779 [math.CO], 2008-2009.
FORMULA
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
a(n) = A060548(n-1) for n >= 2. - Georg Fischer, Nov 03 2018
MATHEMATICA
LinearRecurrence[{0, 0, 0, 0, 0, 2}, {1, 1, 2, 1, 2, 2}, 100] (* Jean-François Alcover, Sep 25 2019 *)
PROG
(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
CROSSREFS
Cf. A060548.
Sequence in context: A351593 A025801 A060548 * A146879 A231577 A325590
KEYWORD
easy,nonn
AUTHOR
Jonathan Vos Post, Jun 18 2008
STATUS
approved

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Last modified March 28 09:04 EDT 2024. Contains 371240 sequences. (Running on oeis4.)