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A323166
Greatest common divisor of Product (1+(p_i^e_i)) and n, when n = Product (p_i^e_i); a(n) = gcd(A034448(n), n).
13
1, 1, 1, 1, 1, 6, 1, 1, 1, 2, 1, 4, 1, 2, 3, 1, 1, 6, 1, 10, 1, 2, 1, 12, 1, 2, 1, 4, 1, 6, 1, 1, 3, 2, 1, 2, 1, 2, 1, 2, 1, 6, 1, 4, 15, 2, 1, 4, 1, 2, 3, 2, 1, 6, 1, 8, 1, 2, 1, 60, 1, 2, 1, 1, 1, 6, 1, 2, 3, 2, 1, 18, 1, 2, 1, 4, 1, 6, 1, 2, 1, 2, 1, 4, 1, 2, 3, 4, 1, 90, 7, 4, 1, 2, 5, 12, 1, 2, 3, 10, 1, 6, 1, 2, 3
OFFSET
1,6
FORMULA
a(n) = gcd(n, A034448(n)), where A034448 is usigma, the sum of unitary divisors of n.
PROG
(PARI)
A034448(n) = { my(f=factorint(n)); prod(k=1, #f~, 1+(f[k, 1]^f[k, 2])); }; \\ After code in A034448
A323166(n) = gcd(n, A034448(n));
CROSSREFS
KEYWORD
nonn
AUTHOR
Antti Karttunen, Jan 09 2019
STATUS
approved