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 A193360 #37 Nov 20 2023 11:54:15 %S A193360 1,1,2,1,2,1,2,3,1,2,1,3,2,3,1,2,3,1,2,3,4,1,2,1,3,1,4,2,3,2,4,3,4,1, %T A193360 2,3,1,2,4,1,3,4,2,3,4,1,2,3,4,1,2,3,4,5,1,2,1,3,1,4,1,5,2,3,2,4,2,5, %U A193360 3,4,3,5,4,5,1,2,3,1,2,4,1,2,5,1,3,4 %N A193360 Concatenation of P{1},P{1,2},P{1,2,3}... where P(A) denotes the power set of A ordered by the size of the subsets, and in each subset, following the increasing order. %C A193360 Fractal sequence. %C A193360 From _Robert Israel_, Jan 09 2023: (Start) %C A193360 Subsets of the same size are ordered lexicographically. %C A193360 The first occurrence of k in this sequence is at position (k - 2)*2^(k - 1) + k + 1. (End) %H A193360 Robert Israel, <a href="/A193360/b193360.txt">Table of n, a(n) for n = 1..10000</a> %p A193360 comp:= proc(a,b) local i; %p A193360 for i from 1 do if a[i] < b[i] then return true elif a[i] > b[i] then return false fi od %p A193360 end proc: %p A193360 [seq(seq(op(map(op, sort(combinat:-choose(n,k),comp))),k=1..n),n=1..6)]; # _Robert Israel_, Jan 09 2023 %p A193360 # second Maple program: %p A193360 T:= n-> map(x-> x[], [seq(combinat[choose]([$1..n], i)[], i=1..n)])[]: %p A193360 seq(T(n), n=1..5); # _Alois P. Heinz_, Jan 30 2023 %t A193360 t={};Do[t=Join[t,Subsets[Range[n]]],{n,1,5}];Flatten[t] %t A193360 Table[Subsets[Range[n]],{n,5}]//Flatten (* _Harvey P. Dale_, May 05 2019 *) %Y A193360 Cf. A082185. %K A193360 nonn,tabf %O A193360 1,3 %A A193360 _José María Grau Ribas_, Jul 24 2011