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 A254969 #9 Sep 22 2021 14:21:31
%S A254969 1,4,2,2,2,2,2,0,2,2,0,0,0,0,0,2,2,0,0,2,0,0,0,2,2,0,2,2,2,2,0,2,2,0,
%T A254969 0,0,0,2,0,2,0,0,2,0,2,0,2,2,0,2,2,2,2,0,0,2,0,0,0,0,2,0,0,0,2,2,0,0,
%U A254969 2,0,2,2,2,0,0,0,0,0,0,0,2,0,0,0,2,0
%N A254969 Central terms of the triangle of iterated absolute differences of lucky numbers.
%H A254969 Reinhard Zumkeller, <a href="/A254969/b254969.txt">Table of n, a(n) for n = 0..1000</a>
%F A254969 a(n) = A254967(2*n,n).
%t A254969 nmax = 85; (* index of last term *)
%t A254969 imax = 600; (* last index of initial lucky array L *)
%t A254969 L = Table[2 i + 1, {i, 0, imax}];
%t A254969 For[n = 2, n < Length[L], r = L[[n++]]; L = ReplacePart[L, Table[r*i -> Nothing, {i, 1, Length[L]/r}]]];
%t A254969 T[n_, n_] := If[n + 1 <= Length[L], L[[n + 1]], Print["imax should be increased"]; 0];
%t A254969 T[n_, k_] := T[n, k] = Abs[T[n, k + 1] - T[n - 1, k]];
%t A254969 a[n_] := T[2n, n];
%t A254969 Table[a[n], {n, 0, nmax}] (* _Jean-François Alcover_, Sep 22 2021 *)
%o A254969 (Haskell)
%o A254969 a254969 n = a254967 (2 * n) n
%Y A254969 Cf. A254967, A000959.
%K A254969 nonn
%O A254969 0,2
%A A254969 _Reinhard Zumkeller_, Feb 11 2015