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A241646
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Numbers m such that the GCD of the x's that satisfy sigma(x)=m is 1.
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5
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1, 12, 18, 24, 31, 32, 42, 48, 54, 56, 60, 72, 80, 84, 90, 96, 98, 104, 108, 114, 120, 128, 132, 140, 144, 152, 156, 168, 180, 182, 192, 216, 224, 228, 234, 240, 248, 252, 264, 270, 272, 280, 288, 294, 308, 312, 324, 336, 342, 360, 372, 384, 390, 408, 420
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OFFSET
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1,2
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LINKS
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EXAMPLE
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We have sigma(6)=sigma(11)=12, and gcd(6, 11) = 1, hence 12 is in the sequence.
For x in [20, 26, 41], sigma(x)=42, and gcd(20, 26, 41)=1, hence 42 is here.
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MAPLE
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N:= 10^4: # for terms <= N
V:= Vector(N):
for x from 1 to N do
s:= numtheory:-sigma(x);
if s <= N then
if V[s] = 0 then V[s]:= x
else V[s]:= igcd(V[s], x)
fi
fi
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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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