A133024 Divisors of 8128, the 4th perfect number.

1, 2, 4, 8, 16, 32, 64, 127, 254, 508, 1016, 2032, 4064, 8128

Offset

1,2

Comments

127 is the 4th Mersenne prime: A000668.

The number of divisors of the 4th perfect number is 2*A000043(4)=A061645(4)=14.

For the structure of this sequence and its binary expansion, see A135654.

Links

Table of n, a(n) for n=1..14.

Index entries for sequences related to divisors of numbers

Omar E. Pol, Determinacion geometrica de los numeros primos y perfectos.

Formula

For n=1..7 : a(n) = 2^(n-1). For n=8..14: a(n) = 2^(n-1) - 2^(n-8) = A000668(4)*2^(n-8).

Mathematica

Divisors[8128] (* Harvey P. Dale, Jul 30 2023 *)

Prog

(PARI) divisors(8128) \\ Charles R Greathouse IV, Jun 21 2017

Crossrefs

Cf. A018254, A018487. Perfect numbers: A000396.

Cf. A000079, A000668, A061645, A133033, A135654.

Sequence in context: A251672 A251747 A251761 * A243085 A060376 A047869

Adjacent sequences: A133021 A133022 A133023 * A133025 A133026 A133027

Keyword

fini,full,nonn,easy

Author

Omar E. Pol, Oct 26 2007, Mar 03 2008, Dec 27 2008

Status

approved