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 A282904 #6 Feb 24 2017 17:56:56
%S A282904 1,1,1,2,1,1,1,2,2,2,3,1,1,1,1,2,2,2,2,2,2,3,3,3,3,4,1,1,1,1,1,2,2,2,
%T A282904 2,2,2,2,2,2,2,3,3,3,3,3,3,3,3,3,3,4,4,4,4,4,5,1,1,1,1,1,1,2,2,2,2,2,
%U A282904 2,2,2,2,2,2,2,2,2,2,3,3,3,3,3,3,3,3,3
%N A282904 Concatenation of the numbers of elements of P{1}, P{1, 2}, P{1, 2, 3}, ..., P{1, 2, 3, ..., n}; where P{A} denote the power set of set A ordered by the size of the subsets, and in each subset, following the increasing order.
%e A282904 Rows with power sets of set of numbers from 1 to n (without nonempty sets):
%e A282904 {1};
%e A282904 {1}, {2}, {1, 2};
%e A282904 {1}, {2}, {3}, {1, 2}, {1, 3}, {2, 3}, {1, 2, 3};
%e A282904 ...
%e A282904 Rows with the number of elements of these subsets:
%e A282904 1;
%e A282904 1, 1, 2;
%e A282904 1, 1, 1, 2, 2, 2, 3;
%e A282904 ...
%e A282904 Concatenation: 1, 1, 1, 2, 1, 1, 1, 2, 2, 2, 3, ...
%Y A282904 Cf. A193360, A282905, A221914.
%K A282904 nonn
%O A282904 1,4
%A A282904 _Jaroslav Krizek_, Feb 24 2017