The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A240908 The sequency numbers of the 8 rows of a version of the Hadamard-Walsh matrix of order 8. 4
 0, 7, 3, 4, 1, 6, 2, 5 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS The Hadamard (Hadamard-Walsh) matrix is widely used in telecommunications and signal analysis. It has 3 well-known forms which vary according to the sequency ordering of its rows: "natural" ordering, "dyadic" or Payley ordering, and sequency ordering.  In a mathematical context the sequency is the number of zero crossings or transitions in a matrix row (although in a physical signal context, it is half the number of zero crossings per time period). The matrix row sequencies are a permutation of the set [0,1,2,...n-1], where n is the order of the matrix. For spectral analysis of signals the sequency-ordered form is needed. Unlike the dyadic ordering (given by A153141), the natural ordering requires a separate list for each matrix order. This sequence is the natural sequency ordering for an order 8 matrix. LINKS N. J. A. Sloane, A Library of Hadamard Matrices Eric Weisstein's World of Mathematics, Hadamard Matrix Wikipedia, Walsh matrix FORMULA Recursion: H(2)=[1 1; 1 -1]; H(n) = H(n-1)*H(2),  where * is Kronecker matrix product. EXAMPLE This is a fixed length sequence of only 8 values, as given. CROSSREFS Cf. A240909 "natural order" sequencies for Hadamard-Walsh matrix, order 16. Cf. A240910 "natural order" sequencies for Hadamard-Walsh matrix, order 32. Cf. A153141 "dyadic order" sequencies for Hadamard-Walsh matrix, all orders. Cf. A000975(n) is sequency of last row of H(n). - William P. Orrick, Jun 28 2015 Sequence in context: A097517 A127559 A066747 * A117043 A013664 A154173 Adjacent sequences:  A240905 A240906 A240907 * A240909 A240910 A240911 KEYWORD nonn,fini,full AUTHOR Ross Drewe, Apr 14 2014 EXTENSIONS Definition of H(n) corrected by William P. Orrick, Jun 28 2015 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified August 5 22:41 EDT 2021. Contains 346488 sequences. (Running on oeis4.)