login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

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.
6
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, 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, 3, 4, 3, 5, 4, 5, 1, 2, 3, 1, 2, 4, 1, 2, 5, 1, 3, 4
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
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
Cf. A082185.
Sequence in context: A136109 A105265 A351468 * A061394 A248141 A220694
KEYWORD
nonn,tabf
AUTHOR
STATUS
approved