OFFSET
1,3
COMMENTS
Fractal sequence.
From Robert Israel, Jan 09 2023: (Start)
Subsets of the same size are ordered lexicographically.
The first occurrence of k in this sequence is at position (k - 2)*2^(k - 1) + k + 1. (End)
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
MAPLE
comp:= proc(a, b) local i;
for i from 1 do if a[i] < b[i] then return true elif a[i] > b[i] then return false fi od
end proc:
[seq(seq(op(map(op, sort(combinat:-choose(n, k), comp))), k=1..n), n=1..6)]; # Robert Israel, Jan 09 2023
# second Maple program:
T:= n-> map(x-> x[], [seq(combinat[choose]([$1..n], i)[], i=1..n)])[]:
seq(T(n), n=1..5); # Alois P. Heinz, Jan 30 2023
MATHEMATICA
t={}; Do[t=Join[t, Subsets[Range[n]]], {n, 1, 5}]; Flatten[t]
Table[Subsets[Range[n]], {n, 5}]//Flatten (* Harvey P. Dale, May 05 2019 *)
CROSSREFS
KEYWORD
nonn,tabf
AUTHOR
José María Grau Ribas, Jul 24 2011
STATUS
approved