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 A133081 #13 Mar 06 2022 08:41:53 %S A133081 1,1,0,0,1,1,0,0,1,0,0,0,0,1,1,0,0,0,0,1,0,0,0,0,0,0,1,1,0,0,0,0,0,0, %T A133081 1,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,1,1,0,0, %U A133081 0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,1,1 %N A133081 An interpolation operator, companion to A133080. %C A133081 A133081 * [1,2,3,...] = A133090: (1, 1, 5, 3, 9, 5, 13, 7, 17, ...). %C A133081 A133080: diagonal and subdiagonal are switched. %F A133081 Infinite lower triangular matrix, (1,0,1,0,...) in the main diagonal and (1,1,1,...) in the subdiagonal. %e A133081 First few rows of the triangle: %e A133081 1; %e A133081 1, 0; %e A133081 0, 1, 1; %e A133081 0, 0, 1, 0; %e A133081 0, 0, 0, 1, 1; %e A133081 ... %o A133081 (PARI) row(n) = vector(n, k, if (k==n-1, 1, if (k==n, n%2))); %o A133081 lista(nn) = my(list=List()); for (n=1, nn, my(v=row(n)); for (k=1, #v, listput(list, v[k]))); Vec(list); \\ _Michel Marcus_, Mar 06 2022 %Y A133081 Cf. A133080, A133090, A040001 (row sums). %K A133081 nonn,easy,tabl %O A133081 1,1 %A A133081 _Gary W. Adamson_, Sep 09 2007 %E A133081 More terms from _Michel Marcus_, Mar 06 2022