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Redheffer Matrix


A Redheffer matrix is a (0,1)-matrix that is square and has elements a_(ij) equal to 1 if j=1 or i|j (i divides j), and 0 otherwise. It is an integer matrix and hence a rational matrix. For n=1, 2, ..., the first few Redheffer matrices are

 [1],[1 1; 1 1],[1 1 1; 1 1 0; 1 0 1],[1 1 1 1; 1 1 0 1; 1 0 1 0; 1 0 0 1].
255x255 Redheffer matrix

The Redheffer matrix of order 255 is illustrated above.

The determinant of the n×n Redheffer matrix is equal to the Mertens function M(n). For n=1, 2, ..., the first few values are therefore 1, 0, -1, -1, -2, -1, -2, -2, -2, ... (OEIS A002321).

The algebraic multiplicity a(n) of the eigenvalue 1 of the n×n Redheffer matrix is

 a(n)=n-|_lgn_|-1

for n>1 (Vaughan 1993, p. 286; Vaughan 1996; Trott 2004, p. 57), where lgn denotes the binary logarithm and |_x_| is the floor function. For n=1, a(1)=1. The first few values for n=1, 2, ... are 1, 0, 1, 1, 2, 3, 4, 4, 5, 6, 7, 8, 9, 10, 11, ... (OEIS A083058).


See also

(0,1)-Matrix, Integer Matrix, Mertens Function, Rational Matrix

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References

Sloane, N. J. A. Sequences A002321/M0102 and A083058 in "The On-Line Encyclopedia of Integer Sequences."Trott, M. The Mathematica GuideBook for Programming. New York: Springer-Verlag, 2004. https://www.mathematicaguidebooks.org/.Vaughan, R. C. "On the Eigenvalues of Redheffer's Matrix. I." In Number Theory with an Emphasis on the Markoff Spectrum (Ed. A. D. Pollington and W. Moran). New York: Dekker, pp. 283-296, 1993.Vaughan, R. C. "On the Eigenvalues of Redheffer's Matrix. II." J. Austral. Math. Soc. 60, 260-273, 1996. https://doi.org/10.1017/S1446788700037654.

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Redheffer Matrix

Cite this as:

Weisstein, Eric W. "Redheffer Matrix." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/RedhefferMatrix.html

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