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%I #9 Dec 28 2020 17:47:13
%S 1,1,1,1,3,1,1,1,5,1,1,1,1,5,3,1,3,1,1,1,9,1,1,1,1,1,3,1,5,1,9,1,1,1,
%T 1,1,1,1,3,1,1,5,1,1,3,1,1,1,1,1,3,1,1,1,3,1,15,1,1,1,3,5,1,1,9,1,1,1,
%U 3,1,1,1,1,1,9,1,1,1,3,1,3,1,1,1,27,1,1,1,1,5,3,1,1,1,81,1,1,1,3,1,1,1,9,1,3,1
%N a(n) = gcd(A019565(2n)-1, A000265(phi(A019565(2n)))).
%H Antti Karttunen, <a href="/A339899/b339899.txt">Table of n, a(n) for n = 0..16384</a>
%H Antti Karttunen, <a href="/A339899/a339899.txt">Data supplement: n, a(n) computed for n = 0..65537</a>
%F a(n) = gcd(A339809(2*n), A339971(n)), where A339971(n) = A053575(A019565(2n)).
%F a(n) = gcd(A339971(n), A339898(n)).
%F a(n) = A339971(n) / A339901(n).
%F a(n) = A000265(A049559(A019565(2*n))).
%o (PARI)
%o A000265(n) = (n>>valuation(n,2));
%o A019565(n) = { my(m=1, p=1); while(n>0, p = nextprime(1+p); if(n%2, m *= p); n >>= 1); (m); };
%o A339899(n) = { my(x=A019565(2*n)); gcd((x-1),A000265(eulerphi(x))); };
%Y Cf. A000010, A000265, A049559, A053575, A019565, A339809, A339821, A339971, A339898, A339901.
%K nonn
%O 0,5
%A _Antti Karttunen_, Dec 28 2020
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