%I A123926
%S A123926 1,1,2,1,2,2,2,1,1,2,2,2,2,2,4,1,2,1,2,6,4,2,2,2,1,2,4,2,2,4,2,3,4,2,4,
%T A123926 1,2,2,4,2,2,4,2,6,2,2,2,2,3,3,4,2,2,4,4,2,4,2,2,12,2,2,2,1,4,4,2,6,4,
               4,
%U A123926 2,1,2,2,2,2,4,4,2,2,1,2,2,4,4,2,4,2,2,2,4,6,4,2,4,6,2,3,2,1,2,4,2,2,8
%N A123926 Greatest common divisor of sigma_k(n) for all k >= 1.
%C A123926 Has the property that if gcd(n,m) = 1, then a(n)*a(m) divides a(n*m). 
               First inequality is a(4) = 1, a(5) = 2, but a(20) = 6. It appears 
               that a(n) also always divides sigma_0(n) = tau(n).
%e A123926 For n=4, sigma_1(n) = 7, sigma_2(n) = 21, both divisible by 7, but sigma_3(n) 
               = 73, which is not, so a(4) = 1.
%Y A123926 Cf. A109974, A000005, A000203, A001157.
%Y A123926 Sequence in context: A082070 A082071 A082902 this_sequence A082064 A082065 
               A082055
%Y A123926 Adjacent sequences: A123923 A123924 A123925 this_sequence A123927 A123928 
               A123929
%K A123926 nice,nonn
%O A123926 1,3
%A A123926 Franklin T. Adams-Watters (FrankTAW(AT)Netscape.net), Nov 21 2006