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 A138815 #9 Mar 20 2022 21:38:17 %S A138815 1,2,4,8,16,32,64,128,256,512,1024,2048,8191,16382,32764,65528,131056, %T A138815 262112,524224,1048448,2096896,4193792,8387584,16775168 %N A138815 Divisors of 16775168 (half the 5th perfect number). %C A138815 The n-th perfect number divided by 2 (A133028(n)) has 2*A090748(n) divisors, then this sequence has 24 members. First 12 members are the first 12 powers of 2 A000079. Last 12 members are multiples of 5th Mersenne prime A000668(5)=8191. a(n) written in base 2 has n digits. See A138825 for the structure of this sequence. %H A138815 <a href="/index/Di#divisors">Index entries for sequences related to divisors of numbers</a> %t A138815 Divisors[16775168] (* _Wesley Ivan Hurt_, Mar 20 2022 *) %o A138815 (PARI) divisors(16775168) \\ _Charles R Greathouse IV_, Jun 22 2017 %Y A138815 Perfect number divided by 2: A133028. Cf. A000043, A000079, A000396, A000668, A090748, A134708, A135655, A138825. %K A138815 easy,fini,full,nonn %O A138815 1,2 %A A138815 _Omar E. Pol_, Mar 31 2008