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 A104974 #17 Sep 08 2022 08:45:17 %S A104974 1,0,1,1,0,1,0,1,0,1,0,0,1,0,1,0,0,0,1,0,1,1,0,0,0,1,0,1,0,1,0,0,0,1, %T A104974 0,1,0,0,1,0,0,0,1,0,1,0,0,0,1,0,0,0,1,0,1,0,0,0,0,1,0,0,0,1,0,1,0,0, %U A104974 0,0,0,1,0,0,0,1,0,1,0,0,0,0,0,0,1,0,0,0,1,0,1,0,0,0,0,0,0,0,1,0,0,0,1,0,1 %N A104974 A Fredholm-Rueppel triangle. %C A104974 Sequence matrix for A036987(n+1). %C A104974 Riordan array ( (Sum_{k>=0} x^(2^k)/x^2) - 1/x, x). %C A104974 Diagonal sums are A070939(n+1), with interpolated zeros. %C A104974 Inverse is A104975. %H A104974 G. C. Greubel, <a href="/A104974/b104974.txt">Rows n = 0..50 of the triangle, flattened</a> %F A104974 T(n, k) = A000108(n+1-k) mod 2. [Corrected by _R. J. Mathar_, Apr 21 2021] %F A104974 Sum_{k=0..n} T(n, k) = A000523(n+1). %e A104974 Triangle begins as: %e A104974 1; %e A104974 0, 1; %e A104974 1, 0, 1; %e A104974 0, 1, 0, 1; %e A104974 0, 0, 1, 0, 1; %e A104974 0, 0, 0, 1, 0, 1; %e A104974 1, 0, 0, 0, 1, 0, 1; %e A104974 0, 1, 0, 0, 0, 1, 0, 1; %e A104974 0, 0, 1, 0, 0, 0, 1, 0, 1; %e A104974 0, 0, 0, 1, 0, 0, 0, 1, 0, 1; %e A104974 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1; %e A104974 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1; %e A104974 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1; %e A104974 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1; %p A104974 A104974 := proc(n,k) %p A104974 modp(A000108(n+1-k),2); %p A104974 end proc: %p A104974 seq(seq( A104974(n,k), k=0..n), n=0..15); # _R. J. Mathar_, Apr 21 2021 %t A104974 Table[Mod[CatalanNumber[n-k+1], 2], {n,0,15}, {k,0,n}]//Flatten (* _G. C. Greubel_, Jun 08 2021 *) %o A104974 (Magma) [(Catalan(n-k+1) mod 2): k in [0..n], n in [0..15]]; // _G. C. Greubel_, Jun 08 2021 %o A104974 (Sage) flatten([[mod(catalan_number(n-k+1), 2) for k in (0..n)] for n in (0..15)]) # _G. C. Greubel_, Jun 08 2021 %Y A104974 Cf. A000523 (row sums), A036987, A070939, A104975. %K A104974 easy,nonn,tabl %O A104974 0,1 %A A104974 _Paul Barry_, Mar 30 2005