%I #14 Jul 30 2023 14:11:18
%S 1,2,4,8,16,32,64,127,254,508,1016,2032,4064,8128
%N Divisors of 8128, the 4th perfect number.
%C 127 is the 4th Mersenne prime: A000668.
%C The number of divisors of the 4th perfect number is 2*A000043(4)=A061645(4)=14.
%C For the structure of this sequence and its binary expansion, see A135654.
%H <a href="/index/Di#divisors">Index entries for sequences related to divisors of numbers</a>
%H Omar E. Pol, <a href="http://www.polrpimos.com">Determinacion geometrica de los numeros primos y perfectos</a>.
%F 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).
%t Divisors[8128] (* _Harvey P. Dale_, Jul 30 2023 *)
%o (PARI) divisors(8128) \\ _Charles R Greathouse IV_, Jun 21 2017
%Y Cf. A018254, A018487. Perfect numbers: A000396.
%Y Cf. A000079, A000668, A061645, A133033, A135654.
%K fini,full,nonn,easy
%O 1,2
%A _Omar E. Pol_, Oct 26 2007, Mar 03 2008, Dec 27 2008