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 A076994 #14 May 13 2024 16:16:12
%S A076994 2,3,5,7,13,23,43,85,167,331,661,1321,2641,5281,10561,21121,42241,
%T A076994 84481,168961,337921,675841,1351681,2703361,5406721,10813441,21626881,
%U A076994 43253761,86507521,173015041,346030081,692060161,1384120321,2768240641
%N A076994 a(1) = 2, a(n+1) is the largest squarefree number < 2*a(n).
%C A076994 Analogous to Bertrand's primes.
%H A076994 Hugo Pfoertner, <a href="/A076994/b076994.txt">Table of n, a(n) for n = 1..360</a>
%p A076994 with(numtheory):a[1] := 2:for n from 2 to 84 do q := 2*a[n-1]-1:while(not issqrfree(q)) do q := q-1:od:a[n] := q:od:seq(a[l],l=1..84);
%t A076994 lsfn[n_]:=Module[{s=2n-1},While[!SquareFreeQ[s],s--];s]; NestList[ lsfn,2,40] (* _Harvey P. Dale_, Nov 28 2018 *)
%Y A076994 Cf. A006992, A076995.
%K A076994 nonn
%O A076994 1,1
%A A076994 _Amarnath Murthy_, Oct 26 2002
%E A076994 More terms from _Sascha Kurz_, Jan 26 2003