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This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A306595 Determinant of the circulant matrix whose first column corresponds to the binary digits of n.

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%I A306595 #23 Mar 06 2019 15:42:14
%S A306595 0,1,1,0,1,2,2,0,1,0,0,3,0,-3,3,0,1,2,2,3,2,3,3,4,2,3,3,4,3,4,4,0,1,0,
%T A306595 4,0,0,-9,9,0,4,9,0,8,9,0,8,5,0,0,9,0,-9,-8,0,-5,0,0,8,5,0,-5,5,0,1,2,
%U A306595 2,3,2,24,24,4,2,3,3,32,3,4,32,5,2,24,3
%N A306595 Determinant of the circulant matrix whose first column corresponds to the binary digits of n.
%C A306595 This sequence is the binary variant of A177894.
%C A306595 From _Robert Israel_, Mar 05 2019: (Start)
%C A306595 a(n) is divisible by A000120(n).
%C A306595 If A070939(n) is even then n is divisible by A000120(n)*A065359(n). (End)
%H A306595 Robert Israel, <a href="/A306595/b306595.txt">Table of n, a(n) for n = 0..10000</a>
%H A306595 Wikipedia, <a href="https://en.wikipedia.org/wiki/Circulant_matrix">Circulant matrix</a>
%H A306595 <a href="/index/Bi#binary">Index entries for sequences related to binary expansion of n</a>
%F A306595 a(A121016(n)) = 0 for any n > 0.
%F A306595 a(2^k) = 1 for any k >= 0.
%F A306595 a(A219325(n)) = A219325(n) for any n > 0.
%e A306595 For n = 13:
%e A306595 - the binary representation of 13 is "1101",
%e A306595 - the corresponding circulant matrix is:
%e A306595     [1 1 0 1]
%e A306595     [1 1 1 0]
%e A306595     [0 1 1 1]
%e A306595     [1 0 1 1]
%e A306595 - its determinant is -3,
%e A306595 - hence a(13) = -3.
%p A306595 a:= n-> `if`(n=1, 1, (l-> LinearAlgebra[Determinant](Matrix(nops(l),
%p A306595        shape=Circulant[l[-i]$i=1..nops(l)])))(convert(n, base, 2))):
%p A306595 seq(a(n), n=0..100);  # _Alois P. Heinz_, Mar 05 2019
%o A306595 (PARI) a(n) = my (d=if (n, binary(n), [0])); my (m=matrix(#d, #d, i,j, d[1+(i-j)%#d])); return (matdet(m))
%Y A306595 Cf. A000120, A065359,  A070939, A121016, A177894, A219325, A306714.
%K A306595 sign,base,look
%O A306595 0,6
%A A306595 _Rémy Sigrist_, Feb 27 2019