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 A139246 #9 Sep 27 2024 05:42:26
%S A139246 1,2,3,1,2,4,7,14,1,2,4,8,16,31,62,124,248,1,2,4,8,16,32,64,127,254,
%T A139246 508,1016,2032,4064,1,2,4,8,16,32,64,128,256,512,1024,2048,4096,8191,
%U A139246 16382,32764,65528,131056,262112,524224,1048448,2096896,4193792,8387584,16775168,1
%N A139246 Triangle read by rows: row n lists the proper divisors of n-th perfect number A000396(n).
%C A139246 Rows n has A133033(n) terms.
%C A139246 The n-th row sum is the n-th perfect number A000396(n).
%H A139246 Omar E. Pol, <a href="http://www.polprimos.com">Determinacion geometrica de los numeros primos y perfectos</a>.
%e A139246 Triangle begins:
%e A139246 1, 2, 3
%e A139246 1, 2, 4, 7, 14
%e A139246 1, 2, 4, 8, 16, 31, 62, 124, 248
%e A139246 1, 2, 4, 8, 16, 32, 64, 127, 254, 508, 1016, 2032, 4064
%e A139246 ...
%t A139246 Table[Most[Divisors[PerfectNumber[n]]],{n,6}]//Flatten (* _Harvey P. Dale_, Jul 08 2024 *)
%Y A139246 Cf. A000396, A018254, A018487, A133024, A133025, A133031, A133033, A135652, A135653, A135654, A135655, A139247.
%K A139246 nonn,tabf
%O A139246 1,2
%A A139246 _Omar E. Pol_, Apr 22 2008, corrected Apr 25 2008