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 A227302 Numbers m such that m divides sigma(2*m). 6
 1, 3, 12, 14, 60, 248, 336, 2160, 2340, 4064, 13104, 15120, 16380, 261888, 1089270, 4455360, 8714160, 10213632, 11784960, 16775168, 22766400, 45981824, 71495424, 98532480, 229909120, 689727360, 738152448, 4291822080, 4294934528, 5100118016, 7091219520 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS If m belongs to the sequence, then sigma(2*m)/m is an integer, so sigma(2*m)/(2*m) is either an integer or half of an integer, so 2*m is either perfect, multiperfect or hemiperfect. - Michel Marcus, Jul 09 2013 LINKS Jinyuan Wang, Table of n, a(n) for n = 1..54 PROG (PARI) is(n)=sigma(2*n)%n==0 \\ Charles R Greathouse IV, Nov 04 2016 CROSSREFS Cf. A000203, A000396, A007691, A159907, A232702. Cf. A141643, A055153, A141645, A159271, A160678. (hemiperfect numbers) Sequence in context: A286386 A032918 A039945 * A201273 A221920 A349663 Adjacent sequences: A227299 A227300 A227301 * A227303 A227304 A227305 KEYWORD nonn AUTHOR Alex Ratushnyak, Jul 05 2013 STATUS approved

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Last modified June 10 04:13 EDT 2023. Contains 363187 sequences. (Running on oeis4.)