OFFSET
2,1
COMMENTS
FORMULA
The entries a(n, m) of row n, for n > = 2 and m = 1, 2, ..., A002541(n), are given by the concatenation of the sequences k*(2, 3, ..., t(n,k)) for k = 1, 2, ..., floor(n/2), with t(n, k) = floor((n-k)/k) + 1.
EXAMPLE
The irregular triangle a(n, m) begins: (the k-sublists are separated by a vertical bar)
n\m 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 ...
-------------------------------------------------------------------------
2: 2
3: 2 3
4: 2 3 4|4
5: 2 3 4 5|4
6: 2 3 4 5 6|4 6|6
7: 2 3 4 5 6 7|4 6| 6
8: 2 3 4 5 6 7 8|4 6 8| 6| 8
9: 2 3 4 5 6 7 8 9| 4 6 8| 6 9| 8
10: 2 3 4 5 6 7 8 9 10| 4 6 8 10| 6 9| 8|10
11: 2 3 4 5 6 7 8 9 10 11| 4 6 8 10| 6 9| 8|10
12: 2 3 4 5 6 7 8 9 10 11 12| 4 6 8 10 12| 6 9 12| 8 12|10|12
13: 2 3 4 5 6 7 8 9 10 11 12 13| 4 6 8 10 12| 6 9 12| 8 12|10|12
...
MATHEMATICA
nrows=10; Table[Flatten[Table[Range[2k, n, k], {k, Floor[n/2]}]], {n, 2, nrows+1}] (* Paolo Xausa, Nov 23 2021 *)
CROSSREFS
KEYWORD
nonn,easy,tabf
AUTHOR
Wolfdieter Lang, Oct 31 2021
STATUS
approved