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 A241649 Numbers m such that the GCD of the x's that satisfy sigma(x)=m is 4. 5
 7, 210, 378, 630, 1904, 3570, 6188, 6510, 7154, 9296, 9800, 10220, 12446, 13664, 14378, 17654, 17780, 18536, 19110, 19376, 19530, 20034, 20580, 21266, 23240, 23310, 24150, 24584, 25298, 26754, 27930, 28938, 29106, 29610, 30380, 31640, 34146, 34230, 34664 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Robert Israel, Table of n, a(n) for n = 1..698 EXAMPLE sigma(104) = sigma(116) = 210, and gcd(104, 116) = 4, hence 210 is in the sequence. Likewise 6510 is obtained with sigma of [2600, 2900, 3464, 3716], with gcd 4. 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]=4, [\$1..N]); # Robert Israel, Aug 18 2019 CROSSREFS Cf. A000203, A240667, A241625, A241646, A241647, A241648, A241650. Sequence in context: A300619 A275822 A065819 * A256288 A302107 A061028 Adjacent sequences: A241646 A241647 A241648 * A241650 A241651 A241652 KEYWORD nonn AUTHOR Michel Marcus, Apr 26 2014 STATUS approved

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Last modified January 29 00:02 EST 2023. Contains 359905 sequences. (Running on oeis4.)