cp's OEIS Frontend

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.

Showing 1-2 of 2 results.

A131062 Rounded frequencies of notes in a Pythagorean scale, starting with 260.7 Hertz for a C.

Original entry on oeis.org

261, 293, 330, 348, 391, 440, 495, 521, 587, 660, 695, 782, 880, 990, 1043, 1173, 1320, 1391, 1564, 1760, 1980, 2086
Offset: 1

Views

Author

Hans Isdahl, Sep 24 2007

Keywords

Comments

The approximate value of 260.7 Hz for the C corresponds to 16/27 * 440 Hz. The frequencies correspond to the ratios [1/1, 9/8, 81/64, 4/3, 3/2, 27/16, 243/128, 2/1].

Links

Crossrefs

Cf. A131071 for the same scale including half-tones.
Cf. A071831/A071832 = A071833/24. - M. F. Hasler, Jun 14 2012
Cf. A101285.

Extensions

Value of a(8) corrected, sequence extended to 3 octaves and comments added by M. F. Hasler (following suggestions by Franklin T. Adams-Watters and Charles R Greathouse IV), Oct 05 2011

A214832 Integer part of A440 piano key frequencies, start with A0 = the 1st key.

Original entry on oeis.org

27, 29, 30, 32, 34, 36, 38, 41, 43, 46, 48, 51, 55, 58, 61, 65, 69, 73, 77, 82, 87, 92, 97, 103, 110, 116, 123, 130, 138, 146, 155, 164, 174, 184, 195, 207, 220, 233, 246, 261, 277, 293, 311, 329, 349, 369, 391, 415, 440, 466, 493, 523, 554, 587, 622, 659, 698, 739, 783, 830, 880, 932, 987, 1046, 1108, 1174, 1244, 1318, 1396, 1479, 1567, 1661, 1760, 1864, 1975, 2093, 2217, 2349, 2489, 2637, 2793, 2959, 3135, 3322, 3520, 3729, 3951, 4186
Offset: 1

Views

Author

Jon Perry, Mar 07 2013

Keywords

Comments

A254531(a(k)) = k, k = 1..88. - Reinhard Zumkeller, Feb 04 2015

Examples

			Middle C is 261.626 Hz so a(40) = 261.

Links

Crossrefs

Cf. A059620, A079731, A131062, A101285, A131071.
Cf. A254531, A010774.

Programs

  • Haskell
    a214832 = floor . (* 440) . (2 **) . (/ 12) . fromIntegral . subtract 49
-- Reinhard Zumkeller, Nov 23 2014
  • JavaScript
    for (i=1;i<=88;i++) document.write(Math.floor(Math.pow(2,(i-49)/12)*440)+", ");
  • PARI
    a(n)=floor(440*2^((n-49)/12));

Formula

a(n) = floor[2^((n-49)/12)*440] (Hz) for 1 <= n <= 88.
Showing 1-2 of 2 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

Content is available under The OEIS End-User License Agreement.