OFFSET
1
COMMENTS
For the construction of this triangle we start with the diagram of A237048.
And then with the diagram of the isosceles triangle of A279693 as shown below:
Row _ _
1 _|1|1|_
2 _|1 _|_ 1|_
3 _|1 |1|1| 1|_
4 _|1 _|0|0|_ 1|_
5 _|1 |1 _|_ 1| 1|_
6 _|1 _|0|1|1|0|_ 1|_
7 _|1 |1 |0|0| 1| 1|_
8 _|1 _|0 _|0|0|_ 0|_ 1|_
9 _|1 |1 |1 _|_ 1| 1| 1|_
10 _|1 _|0 |0|1|1|0| 0|_ 1|_
11 _|1 |1 _|0|0|0|0|_ 1| 1|_
12 _|1 _|0 |1 |0|0| 1| 0|_ 1|_
13 _|1 |1 |0 _|0|0|_ 0| 1| 1|_
14 _|1 _|0 _|0|1 _|_ 1|0|_ 0|_ 1|_
15 _|1 |1 |1 |0|1|1|0| 1| 1| 1|_
16 |1 |0 |0 |0|0|0|0| 0| 0| 1|
...
Then filling the empty cells of the structure with zeros.
Then we replace the 1's that are associated to the even-indexed zig-zag paths in the left hand part of the structure with -1's.
Finally we replace the 1's that are associated to the odd-indexed zig-zag paths in the right hand part of the structure with -1's, as shown below:
Illustration of initial terms as an isosceles triangle:
Row
1 1,-1;
2 1, 0, 0,-1;
3 1, 0,-1, 1, 0,-1;
4 1, 0, 0, 0, 0, 0, 0,-1;
5 1, 0, 0,-1, 0, 0, 1, 0, 0,-1;
6 1, 0, 0, 0, 0, 1,-1, 0, 0, 0, 0,-1;
7 1, 0, 0, 0,-1, 0, 0, 0, 0, 1, 0, 0, 0,-1;
8 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,-1;
9 1, 0, 0, 0, 0,-1, 0, 1, 0, 0,-1, 0, 1, 0, 0, 0, 0,-1;
10 1, 0, 0, 0, 0, 0, 0, 0, 0,-1, 1, 0, 0, 0, 0, 0, 0, 0, 0,-1;
11 1, 0, 0, 0, 0, 0,-1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0,-1;
12 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0,-1, 0, 0, 0, 0, 0, 0, 0, 0,-1;
...
Note that the mentioned triangles are related to isosceles triangle A237593 and to the front view of the pyramid described in A245092.
The position of both the 1's and -1's in the n-th row of the diagram is related to the subparts of the symmetric representation of sigma(n).
The partial sums in row n, except the last term, gives the n-th row of A249351.
EXAMPLE
Triangle begins:
1,-1;
1, 0, 0,-1;
1, 0,-1, 1, 0,-1;
1, 0, 0, 0, 0, 0, 0,-1;
1, 0, 0,-1, 0, 0, 1, 0, 0,-1;
1, 0, 0, 0, 0, 1,-1, 0, 0, 0, 0,-1;
1, 0, 0, 0,-1, 0, 0, 0, 0, 1, 0, 0, 0,-1;
1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,-1;
1, 0, 0, 0, 0,-1, 0, 1, 0, 0,-1, 0, 1, 0, 0, 0, 0,-1;
1, 0, 0, 0, 0, 0, 0, 0, 0,-1, 1, 0, 0, 0, 0, 0, 0, 0, 0,-1;
1, 0, 0, 0, 0, 0,-1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0,-1;
1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0,-1, 0, 0, 0, 0, 0, 0, 0, 0,-1;
...
CROSSREFS
KEYWORD
sign,tabf
AUTHOR
Omar E. Pol, Jan 14 2017
STATUS
approved