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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

Table of n, a(n) for n=0..69.

Jonathan Chappelon, Regular Steinhaus graphs of odd degree, arXiv:0806.2779 [math.CO], 2008-2009.

Index entries for linear recurrences with constant coefficients, signature (0,0,0,0,0,2)

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-Fran├žois 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: A062610 A025801 A060548 * A146879 A231577 A325590

Adjacent sequences:  A140423 A140424 A140425 * A140427 A140428 A140429

KEYWORD

easy,nonn

AUTHOR

Jonathan Vos Post, Jun 18 2008

STATUS

approved

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Last modified October 26 14:28 EDT 2021. Contains 348267 sequences. (Running on oeis4.)