A348031 Multiply-perfect numbers k that have a divisor d such that sigma(d)*d = k.

1, 6, 28, 120, 496, 672, 8128, 30240, 32760, 523776, 23569920, 33550336, 142990848, 1379454720, 8589869056, 66433720320, 137438691328, 153003540480, 403031236608, 14942123276641920, 275502900594021408, 2305843008139952128, 71065075104190073088, 154345556085770649600, 203820700083634254643200, 34384125938411324962897920

Offset

1,2

Comments

Multiply-perfect numbers (A007691) that are present in A064987.

Note how the first three terms of A005820 are included here, while the next three are in A348032.

At least the even terms of A000396 are all present.

Links

Table of n, a(n) for n=1..26.

Index entries for sequences related to sigma(n)

Crossrefs

Intersection of A007691 and A327165.

Cf. A000396, A005820, A064987, A348032 (complement in A007691), A348035 (subsequence).

Sequence in context: A002694 A342924 A007691 * A260508 A334410 A065997

Adjacent sequences: A348028 A348029 A348030 * A348032 A348033 A348034

Keyword

nonn

Author

Antti Karttunen, Sep 26 2021

Status

approved