A329207 Decimal expansion of the fundamental frequency of the note C4 (middle C) in Hertz.

2, 6, 1, 6, 2, 5, 5, 6, 5, 3, 0, 0, 5, 9, 8, 6, 3, 4, 6, 7, 7, 8, 4, 9, 9, 9, 3, 5, 2, 3, 3, 0, 4, 7, 0, 1, 3, 6, 4, 4, 5, 3, 8, 6, 0, 3, 4, 2, 0, 3, 9, 8, 3, 0, 8, 6, 4, 1, 8, 0, 4, 8, 9, 4, 3, 8, 2, 8, 2, 6, 6, 7, 0, 0, 9, 9, 2, 1, 7, 7, 5, 1, 7, 1, 5, 7, 1, 8, 9, 5, 7, 9, 8

Offset

3,1

Comments

In 12-tone equal temperament, when A4 (the fifth A on the Piano keyboard) is tuned to 440 Hz, the frequency of the note C4 (9 semitones below A4) is 440*2^(-9/12) Hz = 261.625... Hz.

Links

Table of n, a(n) for n=3..95.

Wikipedia, Piano key frequencies

Index entries for sequences based on music

Index entries for algebraic numbers, degree 4

Formula

Equals 220 * 2^(1/4).

Example

Frequencies of notes in an octave (Hz):
   >--------------------------------------------------
  |
  |  C4                  261.6255653005...  (this seq)
  |           +---------------------------------------
   >----------| C#4/Db4  277.1826309768...  (A329208)
  |           +---------------------------------------
  |  D4                  293.6647679174...  (A329209)
  |           +---------------------------------------
   >----------| D#4/Eb4  311.1269837220...  (A329210)
  |           +---------------------------------------
  |  E4                  329.6275569128...  (A329211)
  |
   >--------------------------------------------------
  |
  |  F4                  349.2282314330...  (A329212)
  |           +---------------------------------------
   >----------| F#4/Gb4  369.9944227116...  (A329213)
  |           +---------------------------------------
  |  G4                  391.9954359817...  (A329214)
  |           +---------------------------------------
   >----------| G#4/Ab4  415.3046975799...  (A329215)
  |           +---------------------------------------
  |  A4                  440.0000000000
  |           +---------------------------------------
   >----------| A#4/Bb4  466.1637615180...  (A329217)
  |           +---------------------------------------
  |  B4                  493.8833012561...  (A329218)
  |
   >--------------------------------------------------
[New layout from Jon E. Schoenfield, Nov 08 2019]

Prog

(PARI) default(realprecision, 100); 440 * 2^(-9/12)

Crossrefs

See the Example section above for the fundamental frequency of some other notes.

Sequence in context: A076039 A280580 A288872 * A191100 A364708 A322944

Adjacent sequences: A329204 A329205 A329206 * A329208 A329209 A329210

Keyword

nonn,easy,cons

Author

Jianing Song, Nov 08 2019

Extensions

a(93) corrected by Georg Fischer, Jul 16 2021

Status

approved