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 A045989 #14 Mar 20 2024 03:14:23
%S A045989 1,2,3,5,6,9,10,11,13,17,18,21,22,25,26,27,29,34,35,38,42,45,49,50,51,
%T A045989 54,57,58,59,65,66,69,70,74,75,82,85,86,89,91,93,98,99,106,107,109,
%U A045989 114,115,117,122,123,130,131,134,139,141,145,149
%N A045989 a(n) = A045954(n)/2.
%H A045989 Amiram Eldar, <a href="/A045989/b045989.txt">Table of n, a(n) for n = 1..10000</a>
%t A045989 seq[max_] := Module[{lst = Range[2, max, 2], i = 2, len}, While[i <= (len = Length@lst) && (k = lst[[i]]) <= len, lst = Drop[lst, {k, len, k}]; i++]; lst/2]; seq[300] (* _Amiram Eldar_, Mar 20 2024, after _Robert G. Wilson v_ at A045954 *)
%Y A045989 Cf. A045954.
%K A045989 nonn
%O A045989 1,2
%A A045989 _N. J. A. Sloane_