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A241648 Numbers m such that the GCD of the x's that satisfy sigma(x)=m is 3. 5
4, 124, 320, 392, 416, 800, 1352, 1520, 2912, 2960, 3536, 3872, 5720, 5936, 6320, 7112, 8216, 9176, 9912, 10472, 11816, 12152, 12896, 13280, 14960, 15176, 16080, 16400, 16536, 18032, 18392, 18560, 19136, 19880, 20000, 21632, 21680, 21920, 22736, 23120, 23816 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
EXAMPLE
We have sigma(48)=sigma(75)=124, and gcd(48, 75) = 3, hence 124 is in the sequence.
Likewise, we have sigma(x)=2912 for x=[1116, 1236, 1701, 2007, 2181], with gcd 3.
MAPLE
N:= 10^5: # 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
od: select(t -> V[t]=3, [$1..N]); # Robert Israel, Aug 18 2019
CROSSREFS
Sequence in context: A263550 A232592 A005936 * A197779 A197610 A090082
KEYWORD
nonn
AUTHOR
Michel Marcus, Apr 26 2014
STATUS
approved

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Last modified April 22 06:39 EDT 2024. Contains 371888 sequences. (Running on oeis4.)