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 A293429 #13 Oct 16 2017 19:58:54 %S A293429 0,0,1,1,1,1,2,1,1,1,1,2,3,3,3,3,2,2,2,1,2,2,2,2,2,1,1,1,1,2,3,4,4,4, %T A293429 3,3,3,2,3,3,3,3,4,3,2,2,2,3,3,3,3,3,2,2,2,2,3,3,3,3,3,3,3,3,3,4,4,4, %U A293429 4,3,2,2,3,3,4,4,4,4,4,3,3,4,4,5,5,5,4,4,3,3,4,3,4,4,3,3,3,2,2,2,2,3,3,3,3,3 %N A293429 a(0) = 0; and for n > 0, a(n) = a(n-1) + (A008966(4n-1) - A008966(4n+1)). %C A293429 The sequence indicates about a possible bias (or lack of it) in the distribution of squarefree numbers among the numbers of the form 4k-1 vs. the numbers of the form 4k+1. See A293229 for another version. %C A293429 The first negative term is a(4014) = -1. %H A293429 Antti Karttunen, <a href="/A293429/b293429.txt">Table of n, a(n) for n = 0..11111</a> %H A293429 Hans Havermann, <a href="/A293429/a293429.png">Plot of n, a(n) for n = 0..200000</a> %F A293429 a(0) = 0; and for n > 0, a(n) = a(n-1) + (A008966(4n-1) - A008966(4n+1)). %o A293429 (Scheme, with memoization-macro definec) %o A293429 (definec (A293429 n) (if (zero? n) n (+ (- (A008966 (+ -1 (* 4 n))) (A008966 (+ 1 (* 4 n)))) (A293429 (- n 1))))) %Y A293429 Cf. A008966, A293229 (a variant). %K A293429 sign %O A293429 0,7 %A A293429 _Antti Karttunen_, Oct 16 2017