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 A365644 #9 Sep 17 2023 02:47:55
%S A365644 0,0,0,0,1,0,0,11,2,0,0,111,22,3,0,0,1111,222,33,4,0,0,11111,2222,333,
%T A365644 44,5,0,0,111111,22222,3333,444,55,6,0,0,1111111,222222,33333,4444,
%U A365644 555,66,7,0,0,11111111,2222222,333333,44444,5555,666,77,8,0
%N A365644 Array read by ascending antidiagonals: A(n, k) = k*(10^n - 1)/9 with k >= 0.
%F A365644 O.g.f.: x*y/((1 - x)*(1 - 10*x)*(1 - y)^2).
%F A365644 E.g.f.: y*exp(x+y)*(exp(9*x) - 1)/9.
%F A365644 A(n, 11) = A132583(n-1) for n > 0.
%F A365644 A(n, 12) = A073551(n+1) for n > 0.
%e A365644 The array begins:
%e A365644 0, 0, 0, 0, 0, 0, ...
%e A365644 0, 1, 2, 3, 4, 5, ...
%e A365644 0, 11, 22, 33, 44, 55, ...
%e A365644 0, 111, 222, 333, 444, 555, ...
%e A365644 0, 1111, 2222, 3333, 4444, 5555, ...
%e A365644 0, 11111, 22222, 33333, 44444, 55555, ...
%e A365644 ...
%t A365644 A[n_,k_]:=k(10^n-1)/9; Table[A[n-k,k],{n,0,9},{k,0,n}]//Flatten
%Y A365644 Cf. A000004 (n=0 or k=0), A001477 (n=1), A002275 (k=1), A002276 (k=2), A002277 (k=3), A002278 (k=4), A002279 (k=5), A002280 (k=6), A002281 (k=7), A002282 (k=8), A002283 (k=9), A008593 (n=2), A053422 (main diagonal), A105279 (k=10), A132583, A177769 (n=3), A365645 (antidiagonal sums), A365646.
%K A365644 nonn,base,easy,tabl
%O A365644 0,8
%A A365644 _Stefano Spezia_, Sep 14 2023