This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A133025 #14 Jun 21 2017 22:04:26 %S A133025 1,2,4,8,16,32,64,128,256,512,1024,2048,4096,8191,16382,32764,65528, %T A133025 131056,262112,524224,1048448,2096896,4193792,8387584,16775168, %U A133025 33550336 %N A133025 Divisors of 33550336, the 5th perfect number. %C A133025 8191 is the 5th Mersenne prime: A000668. %C A133025 The number of divisors of the 5th perfect number is 2*A000043(5)=A061645(5)=26. %C A133025 For the structure of this sequence and its binary expansion, see A135655. %H A133025 <a href="/index/Di#divisors">Index entries for sequences related to divisors of numbers</a> %H A133025 Omar E. Pol, <a href="http://www.polrpimos.com">Determinacion geometrica de los numeros primos y perfectos</a>. %F A133025 For n=1..13 : a(n) = 2^(n-1). For n=14..26: a(n) = 2^(n-1) - 2^(n-14) = A000668(5)*2^(n-14). %t A133025 Divisors[33550336] (* _Harvey P. Dale_, Jan 24 2015 *) %o A133025 (PARI) divisors(33550336) \\ _Charles R Greathouse IV_, Jun 21 2017 %Y A133025 Cf. A018254, A018487. Perfect numbers: A000396. %Y A133025 Cf. A000043, A000079, A000668, A061645, A133033, A135655. %K A133025 fini,full,nonn,easy %O A133025 1,2 %A A133025 _Omar E. Pol_, Oct 26 2007, Mar 03 2008, Dec 27 2008