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 | 1 |
| 2 | 21 |
| 3 | 321 |
| 4 | 4321 |
| 5 | 54321 |
| 6 | 654321 |
| 7 | 7654321 |
| 8 | 87654321 |
| 9 | 987654321 |
| 10 | 1987654321 |
| 11 | 1987654321 |
| 12 | 101987654321 |
| 13 | 1101987654321 |
| 14 | 11101987654321 |
| 15 | 211101987654321 |
| 16 | 1211101987654321 |
| 17 | 31211101987654321 |
| 18 | 131211101987654321 |
| 19 | 4131211101987654321 |
| 20 | 14131211101987654321 |
| 21 | 514131211101987654321 |