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 A255324 #12 Jan 08 2022 06:32:19
%S A255324 0,0,0,0,0,0,0,0,4,2,0,6,4,2,4,6,8,8,10,10,12,16,12,14,18,18,18,18,20,
%T A255324 22,30,22,26,24,34,26,28,24,30,42,38,42,42,36,40,38,40,36,34,38,48,50,
%U A255324 48,60,56,56,66,62,66,64,72,76,68,70,72,76,80,76,78,72,72,78,74,70,72,84,84,86,84,92,88,84,88,86,94,96,98,104
%N A255324 Difference between the n-th Ludic number and the n-th noncomposite number: a(n) = A003309(n) - A008578(n).
%H A255324 Antti Karttunen, <a href="/A255324/b255324.txt">Table of n, a(n) for n = 1..14000</a>
%F A255324 a(n) = A003309(n) - A008578(n).
%F A255324 a(n) = 2*A255325(n).
%t A255324 t = Range[2, 1000];
%t A255324 A003309 = {1};
%t A255324 While[Length[t]>0, k = t[[1]]; AppendTo[A003309, k]; t = Drop[t, {1, -1, k}]];
%t A255324 a[n_] := If[n == 1, 0, A003309[[n]] - Prime[n - 1]];
%t A255324 Array[a, Length[A003309]] (* _Jean-François Alcover_, Jan 08 2022, after _Ray Chandler_ in A003309 *)
%o A255324 (Scheme) (define (A255324 n) (- (A003309 n) (A008578 n)))
%Y A255324 Cf. A255325 (the same terms halved).
%Y A255324 Cf. A032600, A003309, A008578, A255421, A255422.
%K A255324 nonn
%O A255324 1,9
%A A255324 _Antti Karttunen_, Feb 23 2015