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 A157658 #25 Jul 29 2019 09:55:44 %S A157658 0,1,1,0,1,-1,1,0,0,-1,1,0,1,-1,-1,0,1,0,1,0,-1,-1,1,0,0,-1,0,0,1,1,1, %T A157658 0,-1,-1,-1,0,1,-1,-1,0,1,1,1,0,0,-1,1,0,0,0,-1,0,1,0,-1,0,-1,-1,1,0, %U A157658 1,-1,0,0,-1,1,1,0,-1,1,1,0,1,-1,0,0,-1,1,1,0,0,-1,1,0,-1,-1,-1,0,1,0,-1,0,-1,-1,-1,0,1,0,0,0 %N A157658 a(1) = 0, a(n) = -mu(n) for n >= 2. %C A157658 Except for a(1) the same as A157657. %H A157658 Antti Karttunen, <a href="/A157658/b157658.txt">Table of n, a(n) for n = 1..5000</a> %H A157658 <a href="/index/Eu#epf">Index entries for sequences computed from exponents in factorization of n</a> %F A157658 a(n) = A157657(n), n>1. -- _R. J. Mathar_, Mar 08 2009 %o A157658 (PARI) a(n)=if(n>1,-moebius(n),0) \\ _Charles R Greathouse IV_, Dec 19 2011 %o A157658 (Scheme) (define (A157658 n) (if (= 1 n) 0 (- (A008683 n)))) ;; _Antti Karttunen_, Jul 26 2017 %Y A157658 Cf. A008683, A157657 (same except for a(0)). %Y A157658 Column k = 2 of A144734. %K A157658 sign %O A157658 1,1 %A A157658 _Jaroslav Krizek_, Mar 03 2009 %E A157658 Added more terms, _Joerg Arndt_, Aug 25 2014