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 A168509 #5 Jun 02 2025 02:12:50 %S A168509 1,1,1,1,1,1,1,1,1,1,1,0,1,1,1,1,2,1,1,1,1,1,0,0,1,1,1,1,1,1,1,1,1,1, %T A168509 1,1,1,1,1,0,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,0,0,0,0,1,1,1,1,1,1,1,2, %U A168509 2,2,1,1,1,1,1,1,1,1 %N A168509 Triangle read by rows, A051731 * A101688. %C A168509 Row sums = A079247: (1, 2, 3, 4, 4, 7, 5, 8, 8, 10,...). %C A168509 A168508 = A101688 * A051731 %F A168509 Triangle read by rows, inverse Mobius transform of A101688; where A051731 = the %F A168509 inverse Mobius transform operator. %e A168509 First few rows of the triangle = %e A168509 1; %e A168509 1, 1; %e A168509 1, 1, 1; %e A168509 1, 1, 1, 1; %e A168509 1, 0, 1, 1, 1; %e A168509 1, 2, 1, 1, 1, 1, %e A168509 1, 0, 0, 1, 1, 1, 1; %e A168509 1, 1, 1, 1, 1, 1, 1, 1; %e A168509 1, 1, 1, 0, 1, 1, 1, 1, 1; %e A168509 1, 1, 1, 1, 1, 1, 1, 1, 1, 1; %e A168509 1, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1; %e A168509 1, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1; %e A168509 1, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1; %e A168509 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1; %e A168509 1, 1, 2, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1; %e A168509 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1; %e A168509 1, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1; %e A168509 ... %Y A168509 Cf. A051731, A101688, A079247, A168508 %K A168509 nonn,tabl %O A168509 1,17 %A A168509 _Gary W. Adamson_, Nov 27 2009