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 A002616 M0128 N0052 #31 May 22 2022 04:12:48
%S A002616 1,1,2,1,3,1,3,2,5,1,6,3,2,2,8,3,9,2,3,5,11,1,10,6,9,3,14,2,15,4,5,8,
%T A002616 6,3,18,9,6,2,20,3,21,5,6,11,23,2,21,10,8,6,26,9,10,3,9,14,29,2,30,15,
%U A002616 3,8,6,5,33,8,11,6,35,3,36,18,10,9,15,6,39,2,27,20,41,3,8,21,14,5,44,6,6
%N A002616 Reduced totient function (divided by 2).
%C A002616 A046073 is a similar sequence (the first difference occurs at position 61). - _Artur Jasinski_, Apr 05 2008
%D A002616 D. H. Lehmer, Guide to Tables in the Theory of Numbers. Bulletin No. 105, National Research Council, Washington, DC, 1941, pp. 7-10.
%D A002616 N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
%D A002616 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H A002616 Reinhard Zumkeller, <a href="/A002616/b002616.txt">Table of n, a(n) for n = 3..1000</a>
%H A002616 A. Cauchy, Mémoire sur la résolution des équations indéterminées du premier degré en nombres entiers, <a href="http://gallica.bnf.fr/ark:/12148/bpt6k90204r/f12.image.r">Oeuvres Complètes</a>. Gauthier-Villars, Paris, 1882-1938, Series (2), Vol. 12, pp. 9-47.
%F A002616 a(n) = A002322(n)/2.
%t A002616 Table[CarmichaelLambda[k + 2]/2, {k, 130}] (* _Artur Jasinski_, Apr 05 2008 *)
%o A002616 (Haskell)
%o A002616 a002616 = flip div 2 . a002322 -- _Reinhard Zumkeller_, Sep 02 2014
%o A002616 (PARI) a(n) = lcm(znstar(n)[2])/2; \\ _Michel Marcus_, May 22 2022
%Y A002616 Cf. A002322.
%K A002616 nonn,easy
%O A002616 3,3
%A A002616 _N. J. A. Sloane_
%E A002616 More terms from _Vladeta Jovovic_, Apr 04 2002