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 A131969 #8 Jan 01 2024 23:50:51 %S A131969 3,-2,6,-3,2,-6,3,-2,6,-3,2,-6,3,-2,6,-3,2,-6,3,-2,6,-3,2,-6,3,-2,6, %T A131969 -3,2,-6,3,-2,6,-3,2,-6,3,-2,6,-3,2,-6,3,-2,6,-3,2,-6,3,-2,6,-3,2,-6, %U A131969 3,-2,6,-3,2,-6,3,-2,6,-3,2,-6,3,-2,6,-3,2,-6,3,-2,6,-3,2,-6 %N A131969 First differences of A020806. %F A131969 a(n)=11*(-1)^n/3-2*A010892(n)/3+7*A010892(n-1)/3, n>0. a(n+6)=a(n). G.f.: (3-2x+6x^2)/((1+x)(1-x+x^2)). [From _R. J. Mathar_, Oct 24 2008] %K A131969 sign %O A131969 0,1 %A A131969 _Paul Curtz_, Oct 06 2007