A140426 Number of multi-symmetric Steinhaus matrices of size n.

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

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-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

Adjacent sequences: A140423 A140424 A140425 * A140427 A140428 A140429

Keyword

easy,nonn

Author

Jonathan Vos Post, Jun 18 2008

Status

approved