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.
| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 121 |
| 4 | 10201 |
| 5 | 12321 |
| 6 | 1002001 |
| 7 | 1234321 |
| 8 | 100020001 |
| 9 | 102030201 |
| 10 | 121242121 |
| 11 | 123454321 |
| 12 | 10000200001 |
| 13 | 10221412201 |
| 14 | 12102420121 |
| 15 | 12345654321 |
| 16 | 1000002000001 |
| 17 | 1002003002001 |
| 18 | 1020304030201 |
| 19 | 1022325232201 |
| 20 | 1210024200121 |
| 21 | 1212225222121 |
| 22 | 1232346432321 |
| 23 | 1234567654321 |
| 24 | 100000020000001 |
| 25 | 100220141022001 |