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 A329207 #25 Jun 18 2024 11:08:39 %S A329207 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, %T A329207 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, %U A329207 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 %N A329207 Decimal expansion of the fundamental frequency of the note C4 (middle C) in Hertz. %C A329207 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. %H A329207 Wikipedia, <a href="https://en.wikipedia.org/wiki/Piano_key_frequencies">Piano key frequencies</a> %H A329207 <a href="/index/Mu#music">Index entries for sequences based on music</a> %H A329207 <a href="/index/Al#algebraic_04">Index entries for algebraic numbers, degree 4</a> %F A329207 Equals 220 * 2^(1/4). %e A329207 Frequencies of notes in an octave (Hz): %e A329207 >-------------------------------------------------- %e A329207 | %e A329207 | C4 261.6255653005... (this seq) %e A329207 | +--------------------------------------- %e A329207 >----------| C#4/Db4 277.1826309768... (A329208) %e A329207 | +--------------------------------------- %e A329207 | D4 293.6647679174... (A329209) %e A329207 | +--------------------------------------- %e A329207 >----------| D#4/Eb4 311.1269837220... (A329210) %e A329207 | +--------------------------------------- %e A329207 | E4 329.6275569128... (A329211) %e A329207 | %e A329207 >-------------------------------------------------- %e A329207 | %e A329207 | F4 349.2282314330... (A329212) %e A329207 | +--------------------------------------- %e A329207 >----------| F#4/Gb4 369.9944227116... (A329213) %e A329207 | +--------------------------------------- %e A329207 | G4 391.9954359817... (A329214) %e A329207 | +--------------------------------------- %e A329207 >----------| G#4/Ab4 415.3046975799... (A329215) %e A329207 | +--------------------------------------- %e A329207 | A4 440.0000000000 %e A329207 | +--------------------------------------- %e A329207 >----------| A#4/Bb4 466.1637615180... (A329217) %e A329207 | +--------------------------------------- %e A329207 | B4 493.8833012561... (A329218) %e A329207 | %e A329207 >-------------------------------------------------- %e A329207 [New layout from _Jon E. Schoenfield_, Nov 08 2019] %t A329207 First[RealDigits[220*2^(1/4), 10, 100]] (* _Paolo Xausa_, Jun 18 2024 *) %o A329207 (PARI) default(realprecision, 100); 440 * 2^(-9/12) %Y A329207 See the Example section above for the fundamental frequency of some other notes. %K A329207 nonn,easy,cons %O A329207 3,1 %A A329207 _Jianing Song_, Nov 08 2019 %E A329207 a(93) corrected by _Georg Fischer_, Jul 16 2021