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A323409
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Greatest common divisor of Product (p_i^e_i)-1 and n, when n = Product (p_i^e_i); a(n) = gcd(n, A047994(n)).
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6
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1, 1, 1, 1, 1, 2, 1, 1, 1, 2, 1, 6, 1, 2, 1, 1, 1, 2, 1, 4, 3, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 1, 1, 2, 1, 12, 1, 2, 3, 4, 1, 6, 1, 2, 1, 2, 1, 6, 1, 2, 1, 4, 1, 2, 5, 14, 3, 2, 1, 12, 1, 2, 3, 1, 1, 2, 1, 4, 1, 2, 1, 8, 1, 2, 3, 2, 1, 6, 1, 20, 1, 2, 1, 12, 1, 2, 1, 2, 1, 2, 1, 2, 3, 2, 1, 2, 1, 2, 1, 4, 1, 2, 1, 4, 3
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OFFSET
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1,6
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COMMENTS
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Records 1, 2, 6, 12, 14, 20, 24, 84, 120, 168, 240, 468, 720, 1008, 1240, 1488, 1632, 7440, 9360, 14880, 32640, ... occur at n = 1, 6, 12, 36, 56, 80, 144, 168, 240, 504, 720, 1404, 3600, 4032, 4960, 8928, 13056, 14880, 28080, 44640, 65280, ...
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LINKS
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FORMULA
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PROG
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(PARI)
A047994(n) = { my(f=factor(n)~); prod(i=1, #f, f[1, i]^f[2, i]-1); };
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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