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 A124741 #13 Oct 11 2019 10:58:52
%S A124741 1,1,1,3,1,5,5,7,7,9,7,11,11,13,13,15,13,17,17,19,19,21,19,23,23,25,
%T A124741 25,27,23,29,29,31,31,33,31,35,35,37,37,39,37,41,41,43,43,45,43,47,47,
%U A124741 49,49,51,49,53,53,55,55,57,53,59,59,61,61,63,61,65,65,67,67,69,67,71,71
%N A124741 a(n) = largest of those positive integers which are coprime to both n and n+1 and which are <= n.
%H A124741 Harvey P. Dale, <a href="/A124741/b124741.txt">Table of n, a(n) for n = 1..1000</a>
%e A124741 The positive integers which are coprime to 8 and which are <= 8 are 1,3,5,7. The positive integers which are coprime to 9 and which are <= 9 are 1, 2,4,5,7,8. So a(8) = 7, which is the largest of those integers in both these sequences (1,5,7).
%t A124741 f[n_] := Last @ Select[Range[n], GCD[n, # ] == GCD[n + 1, # ] == 1 &];Table[f[n], {n, 75}] (* _Ray Chandler_, Nov 10 2006 *)
%t A124741 Join[{1},Table[Max[Intersection[Select[Range[n-1],CoprimeQ[ #,n]&],Select[ Range[n-1],CoprimeQ[#,n+1]&]]],{n,2,80}]] (* _Harvey P. Dale_, Jul 08 2018 *)
%Y A124741 Cf. A057475, A124738, A124739, A124740.
%K A124741 nonn
%O A124741 1,4
%A A124741 _Leroy Quet_, Nov 06 2006
%E A124741 Extended by _Ray Chandler_, Nov 10 2006