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Largest prime in the denominator of ratio A341528(n)/A341529(n) (when presented in its lowest terms).
2

%I #10 Mar 28 2021 15:53:28

%S 1,3,5,7,7,5,11,3,13,7,13,7,17,11,7,31,19,13,23,7,11,13,29,5,31,17,5,

%T 11,31,7,37,3,13,19,11,7,41,23,17,7,43,11,47,3,13,29,53,31,11,31,19,

%U 17,59,5,13,11,23,31,61,7,67,37,13,127,17,13,71,19,29,11,73,13,79,41,31,23,13,17,83,31,11,43,89,11

%N Largest prime in the denominator of ratio A341528(n)/A341529(n) (when presented in its lowest terms).

%H <a href="/index/Pri#prime_indices">Index entries for sequences computed from indices in prime factorization</a>

%H <a href="/index/Si#SIGMAN">Index entries for sequences related to sigma(n)</a>

%F a(n) = A006530(A341527(n)).

%o (PARI)

%o A003961(n) = { my(f = factor(n)); for (i=1, #f~, f[i, 1] = nextprime(f[i, 1]+1)); factorback(f); };

%o A006530(n) = if(n>1, vecmax(factor(n)[, 1]), 1);

%o A341527(n) = { my(s=A003961(n)); denominator((sigma(s)*n)/(sigma(n)*s)); };

%o A342668(n) = A006530(A341527(n));

%Y Cf. A000203, A003961, A006530, A341527, A341528, A341529, A342667.

%Y Cf. A341628 (same sequence applied onto prime shift array A246278).

%K nonn

%O 1,2

%A _Antti Karttunen_, Mar 24 2021