A348035 Multiply-perfect numbers k that have a unitary divisor d such that sigma(d)*d = k.

1, 6, 28, 120, 496, 672, 8128, 523776, 33550336, 1379454720, 8589869056, 137438691328, 2305843008139952128, 203820700083634254643200, 2658455991569831744654692615953842176

Offset

1,2

Comments

At least the even terms of A000396 are all present, thus if there are an infinite number of Mersenne primes (A000668), then it implies that this sequence is infinite as well.

Links

Table of n, a(n) for n=1..15.

Index entries for sequences related to sigma(n)

Crossrefs

Subsequence of A348031. Intersection of A007691 and A348034.

Cf. A000396, A000668.

Sequence in context: A260508 A334410 A065997 * A354073 A171476 A171496

Adjacent sequences: A348032 A348033 A348034 * A348036 A348037 A348038

Keyword

nonn

Author

Antti Karttunen, Sep 26 2021

Status

approved