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 A159906 #8 Jun 02 2025 01:39:03 %S A159906 1,1,1,2,-1,2,2,0,0,2,4,-1,-1,-1,4,2,0,2,-1,1,2,6,-1,-1,-1,-1,-1,6,4, %T A159906 0,0,0,0,0,0,4,6,-3,3,0,0,-3,0,0,6,4,2,-1,-3,4,-1,1,-1,1,4,10,-1,-1, %U A159906 -1,-1,-1,-1,-1,-1,-1,10,4,-4,4,2,2,0,0,-2,0,2,0,4 %N A159906 Triangle read by rows, A126988 * A054533. %C A159906 Row sums = n, right and left borders = A000012, phi(n). %F A159906 Triangle read by rows, A126988 * A054533, where A054533 = the lower half of the Ramanujan sum table. %e A159906 First few rows of the triangle = %e A159906 1; %e A159906 1,...1; %e A159906 2,..-1,...2; %e A159906 2,...0,...0,...2; %e A159906 4,..-1,..-1,..-1,...4; %e A159906 2,...0,...2,..-1,...1,...2; %e A159906 6,..-1,..-1,..-1,..-1,..-1,...6; %e A159906 4,...0,...0,...0,...0,...0,...0,...4; %e A159906 6,..-3,...3,...0,...0,..-3,...0,...0,...6; %e A159906 4,...2,..-1,..-3,...4,..-1,...1,..-1,...1,...4; %e A159906 10,.-1,..-1,..-1,..-1,..-1,..-1,..-1,..-1,..-1,...10; %e A159906 4,..-4,...4,...2,...2,...0,...0,..-2,...0,...2,....0,...4; %e A159906 12,.-1,..-1,..-1,..-1,..-1,..-1,..-1,..-1,..-1,...-1,..-1,...12; %e A159906 6,...4,..-1,..-3,..-1,..-3,...6,..-1,...1,..-1,....1,...1,....1,...6; %e A159906 8,..-7,...5,..-2,...8,..-2,...1,...1,..-2,..-4,....1,..-2,....1,...1,...8; %e A159906 8,...0,...0,...0,...0,...0,...0,...0,...0,...0,....0,...0,....0,...0,...0,...8; %e A159906 ... %Y A159906 Cf. A054533, A126988. %K A159906 tabl,sign %O A159906 1,4 %A A159906 _Gary W. Adamson_, Apr 25 2009 %E A159906 a(29) split and more terms from _Georg Fischer_, May 29 2023