OFFSET
1,1
COMMENTS
On the first interpretation, the first three rows are empty. On the second, the first row is (4).
EXAMPLE
The semiprime divisors of 30 are {6,10,15}, so row 30 is (6,10,15). Without empty rows, this is row 19.
Triangle begins (empty rows indicated by dots):
1: .
2: .
3: .
4: 4
5: .
6: 6
7: .
8: 4
9: 9
10: 10
11: .
12: 4,6
Without empty rows:
1: 4
2: 6
3: 4
4: 9
5: 10
6: 4,6
7: 14
8: 15
9: 4
10: 6,9
11: 4,10
12: 21
MATHEMATICA
Table[Select[Divisors[n], PrimeOmega[#]==2&], {n, 100}]
CROSSREFS
KEYWORD
nonn,tabf
AUTHOR
Gus Wiseman, Nov 08 2023
STATUS
approved