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 A078159 #13 Jun 18 2025 21:45:56
%S A078159 2,3,4,7,10,15,21,31,44,63,89,127,180,255,361,511,723,1023,1447,2047,
%T A078159 2895,4095,5791,8191,11584,16383,23169,32767,46339,65535,92680,131071,
%U A078159 185362,262143,370726,524287,741454,1048575,1482909,2097151,2965819,4194303,5931640,8388607
%N A078159 a(n) = A055086(2^n).
%C A078159 a(2n-2)=2^n-1 and a(n)=2a(n-2)+1 generally.
%t A078159 Table[ Length[ Union[ Table[ Floor[2^w/j], {j, 1, 2^w}]]], {w, 1, 25}]
%o A078159 (PARI) a(n) = ceil(2*sqrt(2^n+1)) - 2; \\ _Michel Marcus_, Sep 02 2019
%Y A078159 Cf. A055086, A078160, A078161, A078162.
%K A078159 nonn
%O A078159 1,1
%A A078159 _Labos Elemer_, Nov 27 2002
%E A078159 Extended by _Robert G. Wilson v_, Dec 02 2002
%E A078159 More terms from _Michel Marcus_, Sep 02 2019