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 A016644 #27 Jul 22 2025 06:53:54
%S A016644 3,0,4,4,5,2,2,4,3,7,7,2,3,4,2,2,9,9,6,5,0,0,5,9,7,9,8,0,3,6,5,7,0,5,
%T A016644 4,3,4,2,8,4,5,7,5,2,8,7,4,0,4,6,1,0,6,4,0,1,9,4,0,8,4,4,8,3,5,7,5,0,
%U A016644 7,4,1,5,5,9,7,0,6,7,8,2,3,4,6,6,1,2,7,4,2,5,3,4,0,1,6,0,3,6,1
%N A016644 Decimal expansion of log(21).
%D A016644 Milton Abramowitz and Irene A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards Applied Math. Series 55, 1964 (and various reprintings), p. 2.
%H A016644 Harry J. Smith, <a href="/A016644/b016644.txt">Table of n, a(n) for n = 1..20000</a>
%H A016644 Milton Abramowitz and Irene A. Stegun, eds., <a href="http://www.convertit.com/Go/ConvertIt/Reference/AMS55.ASP">Handbook of Mathematical Functions</a>, National Bureau of Standards, Applied Math. Series 55, Tenth Printing, 1972 [alternative scanned copy].
%H A016644 <a href="/index/Tra#transcendental">Index entries for transcendental numbers</a>
%F A016644 Eqals A016630 + A002391. - _R. J. Mathar_, Jul 22 2025
%e A016644 3.044522437723422996500597980365705434284575287404610640194084483575074....
%t A016644 RealDigits[Log[21], 10, 120][[1]] (* _Harvey P. Dale_, Sep 04 2012 *)
%o A016644 (PARI) default(realprecision, 20080); x=log(21); for (n=1, 20000, d=floor(x); x=(x-d)*10; write("b016644.txt", n, " ", d)); \\ _Harry J. Smith_, May 17 2009, corrected May 20 2009
%Y A016644 Cf. A016449 (continued fraction).
%K A016644 nonn,cons
%O A016644 1,1
%A A016644 _N. J. A. Sloane_