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A325637 Numbers n for which gcd(2n, sigma(n)) = 2n. 4
6, 28, 496, 8128, 30240, 32760, 2178540, 23569920, 33550336, 45532800, 142990848, 1379454720, 8589869056, 43861478400, 66433720320, 137438691328, 153003540480, 403031236608, 704575228896, 181742883469056, 6088728021160320, 14942123276641920, 20158185857531904, 275502900594021408, 622286506811515392, 2305843008139952128 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..1013 (computed from the b-file of A007691 prepared by T. D. Noe, using Flammenkamp's data)

Index entries for sequences where any odd perfect numbers must occur

Index entries for sequences related to sigma(n)

PROG

(PARI) isA325637(n) = ((n+n)==gcd(n+n, sigma(n)));

CROSSREFS

Cf. A000203, A033879, A325636, A325638.

Cf. A000396 (a subsequence).

Subsequence of A007691.

Sequence in context: A138876 A326145 A174633 * A325654 A201186 A060286

Adjacent sequences:  A325634 A325635 A325636 * A325638 A325639 A325640

KEYWORD

nonn

AUTHOR

Antti Karttunen, May 21 2019

STATUS

approved

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Last modified October 23 11:48 EDT 2019. Contains 328345 sequences. (Running on oeis4.)