A354073 Multiply-perfect numbers that are the sum of the divisors of some number.

1, 6, 28, 120, 496, 672, 30240, 32760, 523776, 2178540, 23569920, 33550336, 45532800, 142990848, 459818240, 1379454720, 1476304896, 8589869056, 14182439040, 31998395520, 43861478400, 51001180160, 66433720320, 137438691328, 153003540480, 403031236608, 518666803200

Offset

1,2

Comments

Conjecture: 8128 is only multiply-perfect number that is not in this sequence.

The distinct values of A000203(A066961(n)).

Links

Amiram Eldar, Table of n, a(n) for n = 1..50

Example

The multiply-perfect number 28 is in the sequence because 28 = sigma(12).

Prog

(Magma) Set(Sort([&+Divisors(m): m in [1..10^7] | IsIntegral(&+Divisors(&+Divisors(m)) / &+Divisors(m))]))

Crossrefs

Intersection of A007691 and A002191.

Cf. A000203, A066961, A354072, A354074.

Sequence in context: A334410 A065997 A348035 * A171476 A171496 A006516

Adjacent sequences: A354070 A354071 A354072 * A354074 A354075 A354076

Keyword

nonn

Author

Jaroslav Krizek, May 16 2022

Extensions

a(18)-a(27) from Amiram Eldar, May 12 2024

Status

approved