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a(n) = A003557(n) - 1.
5

%I #5 Jul 28 2020 14:01:35

%S 0,0,0,1,0,0,0,3,2,0,0,1,0,0,0,7,0,2,0,1,0,0,0,3,4,0,8,1,0,0,0,15,0,0,

%T 0,5,0,0,0,3,0,0,0,1,2,0,0,7,6,4,0,1,0,8,0,3,0,0,0,1,0,0,2,31,0,0,0,1,

%U 0,0,0,11,0,0,4,1,0,0,0,7,26,0,0,1,0,0,0,3,0,2,0,1,0,0,0,15,0,6,2,9,0,0,0,3,0

%N a(n) = A003557(n) - 1.

%H Antti Karttunen, <a href="/A336551/b336551.txt">Table of n, a(n) for n = 1..65537</a>

%F a(n) = A066503(n) / A007947(n).

%o (PARI) A336551(n) = { my(f=factor(n)); for(i=1, #f~, f[i, 2] = f[i, 2]-1); (factorback(f)-1); };

%Y Cf. A003557, A007947, A066503.

%K nonn

%O 1,8

%A _Antti Karttunen_, Jul 28 2020