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A241479
GCD of the solutions x of sigma(x) = sigma(n), where sigma(n) = A000203(n) = sum of divisors of n.
4
1, 2, 3, 4, 5, 1, 7, 8, 9, 1, 1, 12, 13, 1, 1, 1, 1, 18, 19, 1, 1, 22, 1, 1, 1, 1, 27, 1, 29, 1, 1, 32, 1, 1, 1, 36, 37, 1, 1, 1, 1, 1, 43, 1, 45, 1, 1, 3, 49, 50, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 61, 1, 1, 64, 1, 1, 67, 2, 1, 1, 1, 72, 73, 1, 3, 1, 1, 1, 1, 2
OFFSET
1,2
COMMENTS
A variant of A240667 without zeros.
LINKS
FORMULA
a(n) = A240667(A000203(n)).
EXAMPLE
a(6)=1 since sigma(6)=12 and sigma(11)=12 and gcd(6, 11) = 1.
PROG
(PARI) sigv(n) = select(i->sigma(i) == n, vector(n, i, i));
a(n) = gcd(sigv(sigma(n)));
CROSSREFS
Sequence in context: A059806 A332425 A286594 * A100994 A375228 A140523
KEYWORD
nonn
AUTHOR
Michel Marcus, Apr 23 2014
STATUS
approved