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 A127201 #13 Oct 28 2019 07:48:13
%S A127201 2,1,3,5,6,6,4,7,8,11,12,11,13,14,15,17,18,18,18,16,19,23,24,25,26,27,
%T A127201 28,26,29,31,32,33,34,35,36,36,35,37,38,41,42,41,43,44,45,47,48,49,50,
%U A127201 51,52,52,52,52,46,53,54,59,60,58,61,62,63,64,65,67,68,69,70,70,68,73
%N A127201 Base-2 logarithms of denominators corresponding to A127200.
%t A127201 Table[Round[(1/Log[2])Log[Denominator[Sum[PrimePi[k]/2^k, {k, 2, x}]]]], {x, 2, 100}]
%o A127201 (PARI) a(n) = logint(denominator(sum(k=2, n, primepi(k)/2^k)), 2); \\ _Michel Marcus_, Oct 28 2019
%Y A127201 Cf. A119523, A127197, A127200.
%K A127201 nonn,frac
%O A127201 2,1
%A A127201 _Artur Jasinski_, Jan 08 2007