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 A329211 #17 Dec 05 2024 19:35:17 %S A329211 3,2,9,6,2,7,5,5,6,9,1,2,8,6,9,9,2,9,7,3,5,8,4,1,7,6,1,0,4,6,5,5,5,0, %T A329211 7,5,1,8,6,4,7,3,3,4,1,8,2,0,9,8,4,3,1,2,8,1,7,0,2,5,2,4,5,7,0,3,1,3, %U A329211 4,6,9,6,0,7,2,3,8,2,1,1,8,5,5,2,0,3,0,9,5,5,3 %N A329211 Decimal expansion of the fundamental frequency of the note E4 in hertz. %C A329211 In 12-tone equal temperament, when A4 (the fifth A on the Piano keyboard) is tuned to 440 Hz, the frequency of the note E4 (5 semitones below A4) is 440*2^(-5/12) Hz = 329.6 Hz. %C A329211 Also the frequency of the first string of a guitar when standard tuning is used. %H A329211 Wikipedia, <a href="https://en.wikipedia.org/wiki/Piano_key_frequencies">Piano key frequencies</a> %H A329211 <a href="/index/Mu#music">Index entries for sequences based on music</a> %H A329211 <a href="/index/Al#algebraic_12">Index entries for algebraic numbers, degree 12</a> %F A329211 Equals 220 * 2^(7/12). %e A329211 Frequencies of notes in an octave (Hz): %e A329211 >-------------------------------------------------- %e A329211 | %e A329211 | C4 261.6255653005... (A329207) %e A329211 | +--------------------------------------- %e A329211 >----------| C#4/Db4 277.1826309768... (A329208) %e A329211 | +--------------------------------------- %e A329211 | D4 293.6647679174... (A329209) %e A329211 | +--------------------------------------- %e A329211 >----------| D#4/Eb4 311.1269837220... (A329210) %e A329211 | +--------------------------------------- %e A329211 | E4 329.6275569128... (this seq) %e A329211 | %e A329211 >-------------------------------------------------- %e A329211 | %e A329211 | F4 349.2282314330... (A329212) %e A329211 | +--------------------------------------- %e A329211 >----------| F#4/Gb4 369.9944227116... (A329213) %e A329211 | +--------------------------------------- %e A329211 | G4 391.9954359817... (A329214) %e A329211 | +--------------------------------------- %e A329211 >----------| G#4/Ab4 415.3046975799... (A329215) %e A329211 | +--------------------------------------- %e A329211 | A4 440.0000000000 %e A329211 | +--------------------------------------- %e A329211 >----------| A#4/Bb4 466.1637615180... (A329217) %e A329211 | +--------------------------------------- %e A329211 | B4 493.8833012561... (A329218) %e A329211 | %e A329211 >-------------------------------------------------- %e A329211 [New layout from _Jon E. Schoenfield_, Nov 08 2019] %t A329211 First[RealDigits[220*2^(7/12), 10, 100]] (* _Paolo Xausa_, Jun 18 2024 *) %o A329211 (PARI) default(realprecision, 100); 440 * 2^(-5/12) %Y A329211 See the Example section above for the fundamental frequency of some other notes. %K A329211 nonn,easy,cons %O A329211 3,1 %A A329211 _Jianing Song_, Nov 08 2019