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 A277889 #7 Nov 14 2016 10:36:23 %S A277889 0,1,0,-1,0,1,0,-1,0,-1,0,-1,-2,-1,-2,-3,-2,-1,-2,-1,0,-1,0,1,0,1,0, %T A277889 -1,0,-1,-2,-1,0,-1,-2,-1,-2,-1,-2,-1,-2,-3,-2,-1,-2,-1,-2,-3,-2,-3, %U A277889 -4,-3,-2,-3,-2,-1,-2,-1,-2,-3,-4,-3,-4,-3,-2,-3,-2,-1,-2,-1,-2,-1,-2,-3,-2,-1,-2,-1,-2,-1,0,-1,0,1,2,1,0 %N A277889 After zero, excess of the odd terms in A276573 (the infinite trunk of least squares beanstalk) over the even terms. %C A277889 Is a(2358) = 0 the last zero of this sequence? See also comments in A277891. %H A277889 Antti Karttunen, <a href="/A277889/b277889.txt">Table of n, a(n) for n = 0..41014</a> %F A277889 a(0) = 0; for n >= 1, a(n) = a(n-1) - (-1)^A276573(n). %o A277889 (Scheme, with memoization-macro definec) %o A277889 (definec (A277889 n) (if (zero? n) n (- (A277889 (- n 1)) (expt -1 (A276573 n))))) %Y A277889 Cf. A002828, A276573, A277890, A277891. %K A277889 sign %O A277889 0,13 %A A277889 _Antti Karttunen_, Nov 13 2016