OFFSET
1,2
COMMENTS
Note that every row ends when it is easy to know the next missing terms because they are powers of 2 or the last term and the next missing terms form a row that it is already in the sequence.
For a square array with infinitely many terms in every row, see A347270, which is a supersequence that contains all 3x+1 sequences.
LINKS
EXAMPLE
Triangle begins:
1;
2;
3, 10, 5, 16;
4;
5, 16;
6, 3;
7, 22, 11, 34, 17, 52, 26, 13, 40, 20, 10, 5;
8;
9, 28, 14, 7;
10, 5;
11, 34, 17, 52, 26, 13, 40, 20, 10;
12, 6;
13, 40, 20, 10;
14, 7;
15, 46, 23, 70, 35, 106, 53, 160, 80, 40, 20, 10;
16;
17, 52, 26, 13;
18, 9;
19, 58, 29, 88, 44, 22, 11;
...
For n = 3 the 3x+1 trajectory is 3, 10, 5, 16, 8, 4, 2, 1, 4, 2, 1, ... The fourth term is 16 which is a power of 2 so the third row of the triangle is [3, 10, 5, 16].
For n = 6 the 3x+1 trajectory is 6, 3, 10, 5, 16, 8, 4, 2, 1, 4, 2, 1, ... The second term is 3 which is less than 6 so the 6th row of the triangle is [6, 3].
CROSSREFS
KEYWORD
nonn,tabf
AUTHOR
Omar E. Pol, Aug 25 2021
STATUS
approved