%I #34 Oct 14 2019 11:17:27
%S 27,29,30,32,34,36,38,41,43,46,48,51,55,58,61,65,69,73,77,82,87,92,97,
%T 103,110,116,123,130,138,146,155,164,174,184,195,207,220,233,246,261,
%U 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
%N Integer part of A440 piano key frequencies, start with A0 = the 1st key.
%C A254531(a(k)) = k, k = 1..88. - _Reinhard Zumkeller_, Feb 04 2015
%H BGfL, <a href="http://www.bgfl.org/custom/resources_ftp/client_ftp/ks2/music/piano/index.htm">A Virtual Keyboard</a>
%H Wikipedia, <a href="http://en.wikipedia.org/wiki/Piano_key_frequencies">Piano Key Frequencies</a>
%H Wikipedia, <a href="http://en.wikipedia.org/wiki/Twelfth_root_of_two">Twelfth root of two</a>
%H <a href="/index/Mu#music">Index entries for sequences based on music</a>
%F a(n) = floor[2^((n-49)/12)*440] (Hz) for 1 <= n <= 88.
%e Middle C is 261.626 Hz so a(40) = 261.
%o (JavaScript)
%o for (i=1;i<=88;i++) document.write(Math.floor(Math.pow(2,(i-49)/12)*440)+", ");
%o (PARI) a(n)=floor(440*2^((n-49)/12));
%o (Haskell)
%o a214832 = floor . (* 440) . (2 **) . (/ 12) . fromIntegral . subtract 49
%o -- _Reinhard Zumkeller_, Nov 23 2014
%Y Cf. A059620, A079731, A131062, A101285, A131071.
%Y Cf. A254531, A010774.
%K nonn,fini,full
%O 1,1
%A _Jon Perry_, Mar 07 2013