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 A191613 #31 Dec 17 2017 03:07:54
%S A191613 0,0,1,1,2,1,2,1,2,2,2,1,4,2,2,2,4,2,3,2,2,2,2,1,4,4,3,2,4,2,4,3,2,4,
%T A191613 4,2,6,3,4,2,6,2,4,2,4,2,2,2,4,4,4,4,4,3,4,2,3,4,2,2,8,4,2,4,4,2,4,4,
%U A191613 2,4,4,2,9,6,4,3,4,4,4,2,4,6,2,2,4,4,4,2,6,4,4,2,4,2,6,3,10,4,4,4,6,4,4,4,4
%N A191613 Number of even divisors of lambda(n).
%C A191613 Lambda is the function in A002322.
%H A191613 Antti Karttunen, <a href="/A191613/b191613.txt">Table of n, a(n) for n = 1..16384</a>
%F A191613 a(n) = A183063(A002322(n)). - _Michel Marcus_, Mar 18 2016
%e A191613 a(13) = 4 because lambda(13) = 12 and the 4 even divisors are { 2, 4, 6, 12}.
%t A191613 f[n_] := Block[{d = Divisors[CarmichaelLambda[n]]}, Count[EvenQ[d], True]]; Table[f[n], {n, 80}]
%t A191613 (* Second program: *)
%t A191613 Array[DivisorSum[CarmichaelLambda@ #, 1 &, EvenQ] &, 105] (* _Michael De Vlieger_, Dec 04 2017 *)
%o A191613 (PARI) a(n) = sumdiv(lcm(znstar(n)[2]), d, 1-(d%2)); \\ _Michel Marcus_, Mar 18 2016
%Y A191613 Cf. A002322, A183063, A193322, A193386.
%K A191613 nonn
%O A191613 1,5
%A A191613 _Michel Lagneau_, Jul 22 2011
%E A191613 More terms from _Antti Karttunen_, Dec 04 2017