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A345937 a(n) = gcd(n-1, uphi(n)), where uphi is unitary totient (or unitary phi) function, A047994.

%I A345937 #12 Jul 02 2021 03:47:08
%S A345937 1,1,2,3,4,1,6,7,8,1,10,1,12,1,2,15,16,1,18,1,4,1,22,1,24,1,26,9,28,1,
%T A345937 30,31,4,1,2,1,36,1,2,1,40,1,42,1,4,1,46,1,48,1,2,3,52,1,2,1,4,1,58,1,
%U A345937 60,1,2,63,16,5,66,1,4,3,70,1,72,1,2,3,4,1,78,1,80,1,82,1,4,1,2,1,88,1,18,1,4,1,2,1,96
%N A345937 a(n) = gcd(n-1, uphi(n)), where uphi is unitary totient (or unitary phi) function, A047994.
%H A345937 Antti Karttunen, <a href="/A345937/b345937.txt">Table of n, a(n) for n = 1..16384</a>
%F A345937 a(n) = gcd(n-1, A047994(n)).
%F A345937 a(n) = A047994(n) / A345938(n).
%F A345937 a(n) = (n-1) / A345939(n), for n > 1.
%F A345937 a(2n-1) = A345947(2n-1), for n >= 1.
%o A345937 (PARI)
%o A345937 A047994(n) = { my(f=factor(n)~); prod(i=1, #f, (f[1, i]^f[2, i])-1); };
%o A345937 A345937(n) = gcd(n-1, A047994(n));
%Y A345937 Cf. A047994, A345938, A345939.
%Y A345937 Cf. also A049559, A340087, A323409, A345947.
%K A345937 nonn
%O A345937 1,3
%A A345937 _Antti Karttunen_, Jun 29 2021