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 A160115 #11 Jul 22 2025 06:24:39 %S A160115 0,0,1,0,1,0,1,1,1,1,2,2,3,0,-1,-1,1,2,0,-1,0,2,6,1,2,7,5,-1,-7,-4,4, %T A160115 -7,-21,-7,-2,30,2,14,-8,7,-1,-7,-12,-1,21,28,7,-29,-33,-76,-88,15,47, %U A160115 58,-51,-112,293,122,316,-96,-42,-259,140,-111,6,-790,-342,146,395,1087 %N A160115 Fluctuations of the number of cubefree integers not exceeding 2^n. %C A160115 The asymptotic density of cubefree integers is the reciprocal of Apery's constant 1/zeta(3) = 0.83190737258... The number of cubefree integers not exceeding N is thus roughly N/zeta(3). When N is a power of 2, this sequence gives the difference between the actual number (A160113) and that linear estimate (rounded to the nearest integer). %H A160115 Chai Wah Wu, <a href="/A160115/b160115.txt">Table of n, a(n) for n = 0..99</a> %H A160115 G. P. Michon, <a href="http://www.numericana.com/answer/constants.htm#apery">Reciprocal of Apery's constant</a>. %H A160115 G. P. Michon, <a href="http://www.numericana.com/answer/counting.htm#cubefree">On the number of cubefree integers not exceeding N</a>. %H A160115 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Cubefree.html">Cubefree</a>. %F A160115 a(n) = A160113(n)-round(2^n/zeta(3)) %Y A160115 A004709 (cubefree integers). A160112 & A160113 (counting cubefree integers). %K A160115 easy,sign %O A160115 0,11 %A A160115 _Gerard P. Michon_, May 06 2009