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 A334568 #17 May 09 2020 02:41:37
%S A334568 1,1,-1,1,-1,1,1,-1,0,-1,1,-1,0,2,1,1,-1,0,0,-2,-1,1,-1,0,0,6,-6,1,1,
%T A334568 -1,0,0,0,-6,16,-1,1,-1,0,0,0,24,-24,20,1,1,-1,0,0,0,0,-24,-120,-132,
%U A334568 -1,1,-1,0,0,0,0,120,-120,540,-28,1,1,-1,0,0,0,0,0,-120,-720,1764,1216,-1
%N A334568 Square array A(n,k), n >= 0, k >= 1, read by antidiagonals downwards, where column k is the expansion of e.g.f. exp(-Sum_{j=1..k} x^j/j).
%H A334568 Seiichi Manyama, <a href="/A334568/b334568.txt">Antidiagonals n = 0..139, flattened</a>
%F A334568 A(0,k) = 1 and A(n,k) = - (n-1)! * Sum_{j=1..min(k,n)} A(n-j,k)/(n-j)!.
%e A334568 Square array begins:
%e A334568 1, 1, 1, 1, 1, 1, 1, ...
%e A334568 -1, -1, -1, -1, -1, -1, -1, ...
%e A334568 1, 0, 0, 0, 0, 0, 0, ...
%e A334568 -1, 2, 0, 0, 0, 0, 0, ...
%e A334568 1, -2, 6, 0, 0, 0, 0, ...
%e A334568 -1, -6, -6, 24, 0, 0, 0, ...
%e A334568 1, 16, -24, -24, 120, 0, 0, ...
%e A334568 -1, 20, -120, -120, -120, 720, 0, ...
%e A334568 1, -132, 540, -720, -720, -720, 5040, ...
%Y A334568 Columns k=1..5 give A033999, A001464, A334569, A334570, A334571.
%Y A334568 Cf. A330858, A334561.
%K A334568 sign,tabl
%O A334568 0,14
%A A334568 _Seiichi Manyama_, May 06 2020