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.
%I A240909 #31 Feb 16 2025 08:33:21 %S A240909 0,15,7,8,3,12,4,11,1,14,6,9,2,13,5,10 %N A240909 The sequency numbers of the 16 rows of a Hadamard-Walsh matrix of order 16. %C A240909 See A240908 for context. This sequence is the natural sequency ordering for an order 16 matrix. %H A240909 N. J. A. Sloane, <a href="http://neilsloane.com/hadamard">A Library of Hadamard Matrices</a> %H A240909 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/HadamardMatrix.html">Hadamard Matrix</a> %H A240909 Wikipedia, <a href="http://en.wikipedia.org/wiki/Walsh_matrix">Walsh matrix</a> %F A240909 Recursion: H(2)=[1 1; 1 -1]; H(n) = H(n-1)*H(2), where * is Kronecker matrix product. %F A240909 a(n) = A131271(4,n) - 1. - _Mathew Englander_, Jun 19 2021 %e A240909 This is a fixed length sequence of only 16 values, as given. %Y A240909 Cf. A240908 "natural order" sequencies for Hadamard-Walsh matrix, order 8. %Y A240909 Cf. A240910 "natural order" sequencies for Hadamard-Walsh matrix, order 32. %Y A240909 Cf. A153141 "dyadic order" sequencies for Hadamard-Walsh matrix, all orders. %Y A240909 Cf. A000975(n) is sequency of last row of H(n). - _William P. Orrick_, Jun 28 2015 %Y A240909 Cf. A131271 (row 4, minus 1). %K A240909 nonn,fini,full %O A240909 1,2 %A A240909 _Ross Drewe_, Apr 14 2014 %E A240909 Definition of H(n) corrected by _William P. Orrick_, Jun 28 2015