This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
The top left 8 X 8 corner of A163357: 0 1 14 15 16 19 20 21 3 2 13 12 17 18 23 22 4 7 8 11 30 29 24 25 5 6 9 10 31 28 27 26 58 57 54 53 32 35 36 37 59 56 55 52 33 34 39 38 60 61 50 51 46 45 40 41 63 62 49 48 47 44 43 42 The top left 9 X 9 corner of A163336: 0 5 6 47 48 53 54 59 60 1 4 7 46 49 52 55 58 61 2 3 8 45 50 51 56 57 62 15 14 9 44 39 38 69 68 63 16 13 10 43 40 37 70 67 64 17 12 11 42 41 36 71 66 65 18 23 24 29 30 35 72 77 78 19 22 25 28 31 34 73 76 79 20 21 26 27 32 33 74 75 80 12 is in position (1,3) in A163357, while A163336(1,3) = 46. Thus a(12) = 46.
The first 5 rows of this triangle show how this curve begins (connect the terms in numerical order):
1;
2, 0;
0, 3, 4;
9, 8, 0, 5;
10, 0, 7, 6, 0;
...
The top left corner of the array shows how this curve begins (connect the terms in numerical order): 1 0 5 6 7 2 3 4 0 8 0 0 0 10 9 0 0 0 11 0 0 0 0 12 13 20 19 18 0 14 21 0 17 16 15 22 23 0 0 0 0 24 0 0 0 26 25 0 0 0 27 0 31 32 33 28 29 30 0 34
Array T(n, k) begins:
n\k| 0 1 2 3 4 5 6 7 8
---+------------------------------------
0 | 1 6---7 16--17--18--19 24--25
| | | | | | | |
1 | 2 5 8 15--14--13 20 23 26
| | | | | | | |
2 | 3---4 9--10--11--12 21--22 27
| |
3 | 48--47--46--45 40--39 30--29--28
| | | | | |
4 | 49--50--51 44 41 38 31--32--33
| | | | | |
5 | 54--53--52 43--42 37--36--35--34
| |
6 | 55 60--61 70--71--72--73 78--79
| | | | | | | |
7 | 56 59 62 69--68--67 74 77 80
| | | | | | | |
8 | 57--58 63--64--65--66 75--76 81
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