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Smallest number k such that sigma(tau(k)) = n, or 0 if there is no such k.
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%I #15 Jan 15 2013 22:02:01

%S 1,0,2,4,0,16,6,64,0,0,0,12,36,4096,24,0,0,48,0,262144,0,0,0,192,0,0,

%T 0,60,0,268435456,120,576,0,0,0,3072,0,68719476736,180,900,0,240,0,

%U 4398046511104,0,0,0,9216,0,0,0,0,0,196608,0,960,46656,0,0,360,0,1152921504606846976

%N Smallest number k such that sigma(tau(k)) = n, or 0 if there is no such k.

%C Smallest number k such that A062069(k) = A000203(A000005(k)) = n, or 0 if there is no such k.

%F a(n)=0 iff A051444(n) = 0.

%e a(6) = 16 because number 16 is the smallest number k such that sigma(tau(k)) = 6; (tau(16)=5, sigma(5)=6).

%Y Cf. A062069 (sigma(tau(n))), A000203(sigma(n)), A000005(tau(n)).

%K nonn

%O 1,3

%A _Jaroslav Krizek_, Jan 02 2013