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 A329209 #13 Aug 21 2023 11:13:55 %S A329209 2,9,3,6,6,4,7,6,7,9,1,7,4,0,7,5,6,0,2,6,2,7,8,3,0,1,3,8,6,0,5,7,9,6, %T A329209 1,0,4,8,0,7,2,5,8,4,6,7,7,7,5,4,3,6,2,5,3,2,6,5,7,3,5,7,8,6,7,4,5,8, %U A329209 8,5,4,6,9,2,5,0,5,0,6,2,4,5,2,1,7,2,5,9,5,0,0 %N A329209 Decimal expansion of the fundamental frequency of the note D4 in hertz. %C A329209 In 12-tone equal temperament, when A4 (the fifth A on the Piano keyboard) is tuned to 440 Hz, the frequency of the note D4 (7 semitones below A4) is 440*2^(-7/12) Hz = 293.7 Hz. %H A329209 Wikipedia, <a href="https://en.wikipedia.org/wiki/Piano_key_frequencies">Piano key frequencies</a> %H A329209 <a href="/index/Mu#music">Index entries for sequences based on music</a> %H A329209 <a href="/index/Al#algebraic_12">Index entries for algebraic numbers, degree 12</a> %F A329209 Equals 220 * 2^(5/12). %e A329209 Frequencies of notes in an octave (Hz): %e A329209 >-------------------------------------------------- %e A329209 | %e A329209 | C4 261.6255653005... (A329207) %e A329209 | +--------------------------------------- %e A329209 >----------| C#4/Db4 277.1826309768... (A329208) %e A329209 | +--------------------------------------- %e A329209 | D4 293.6647679174... (this seq) %e A329209 | +--------------------------------------- %e A329209 >----------| D#4/Eb4 311.1269837220... (A329210) %e A329209 | +--------------------------------------- %e A329209 | E4 329.6275569128... (A329211) %e A329209 | %e A329209 >-------------------------------------------------- %e A329209 | %e A329209 | F4 349.2282314330... (A329212) %e A329209 | +--------------------------------------- %e A329209 >----------| F#4/Gb4 369.9944227116... (A329213) %e A329209 | +--------------------------------------- %e A329209 | G4 391.9954359817... (A329214) %e A329209 | +--------------------------------------- %e A329209 >----------| G#4/Ab4 415.3046975799... (A329215) %e A329209 | +--------------------------------------- %e A329209 | A4 440.0000000000 %e A329209 | +--------------------------------------- %e A329209 >----------| A#4/Bb4 466.1637615180... (A329217) %e A329209 | +--------------------------------------- %e A329209 | B4 493.8833012561... (A329218) %e A329209 | %e A329209 >-------------------------------------------------- %e A329209 [New layout from _Jon E. Schoenfield_, Nov 08 2019] %t A329209 RealDigits[440 1/Surd[2^7,12],10,120][[1]] (* _Harvey P. Dale_, Aug 01 2021 *) %o A329209 (PARI) default(realprecision, 100); 440 * 2^(-7/12) %Y A329209 See the Example section above for the fundamental frequency of some other notes. %K A329209 nonn,easy,cons %O A329209 3,1 %A A329209 _Jianing Song_, Nov 08 2019