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Card( k>0 : sigma(k)=sigma(n) ).
5

%I #10 Nov 07 2017 18:30:14

%S 1,1,1,1,1,2,1,1,1,2,2,1,1,3,3,2,2,1,1,3,2,1,3,3,2,3,1,2,1,5,2,1,3,2,

%T 3,1,1,3,2,3,3,4,1,3,1,5,3,2,1,1,5,2,2,4,5,4,2,3,3,6,1,4,2,1,3,5,1,2,

%U 4,5,5,1,1,2,2,2,4,6,2,2,1,2,3,3,2,2,4,4,3,3,1,6,2,5,4,6,2,1,2,1,1,5,2,2,5

%N Card( k>0 : sigma(k)=sigma(n) ).

%H Antti Karttunen, <a href="/A070242/b070242.txt">Table of n, a(n) for n = 1..16384</a>

%F a(n) = A054973(A000203(n)). - _Antti Karttunen_, Nov 07 2017

%o (PARI) for(n=1,150,print1(sum(i=1,10*n,if(sigma(n)-sigma(i),0,1)),","))

%o (PARI) A070242(n) = { my(s=sigma(n)); length(select(i->sigma(i) == s, vector(s, i, i))); } \\ _Antti Karttunen_, Nov 07 2017

%o (PARI) A070242(n) = { my(s=sigma(n)); sum(k=1, s, (sigma(k)==s)); }; \\ _Antti Karttunen_, Nov 07 2017

%Y Cf. A000203, A054973, A066412.

%K easy,nonn

%O 1,6

%A _Benoit Cloitre_, May 09 2002