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A355003
a(n) = gcd(A003415(n), A277791(n)), where A003415 is the arithmetic derivative and A277791 is the denominator of sum of reciprocals of proper divisors of n.
3
1, 1, 1, 2, 1, 1, 1, 4, 3, 1, 1, 4, 1, 1, 1, 8, 1, 3, 1, 4, 1, 1, 1, 4, 5, 1, 9, 4, 1, 1, 1, 16, 1, 1, 1, 2, 1, 1, 1, 4, 1, 1, 1, 4, 3, 1, 1, 16, 7, 5, 1, 4, 1, 27, 1, 4, 1, 1, 1, 4, 1, 1, 3, 32, 1, 1, 1, 4, 1, 1, 1, 12, 1, 1, 5, 4, 1, 1, 1, 16, 27, 1, 1, 4, 1, 1, 1, 4, 1, 3, 1, 4, 1, 1, 1, 16, 1, 7, 3, 5, 1, 1, 1, 4, 1
OFFSET
1,4
LINKS
FORMULA
a(n) = gcd(A003415(n), A277791(n)).
a(p^k) = p^(k-1) for all primes p and exponents k > 0.
PROG
(PARI)
A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
A277791(n) = denominator((sigma(n)-1)/n); \\ From A277791
A355003(n) = gcd(A003415(n), A277791(n));
CROSSREFS
Cf. also A355815.
Sequence in context: A128708 A087653 A295666 * A322020 A294895 A285328
KEYWORD
nonn
AUTHOR
Antti Karttunen, Jul 18 2022
STATUS
approved