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 | 9 |
| 2 | 49 |
| 3 | 249 |
| 4 | 1249 |
| 5 | 81249 |
| 6 | 781249 |
| 7 | 5781249 |
| 8 | 25781249 |
| 9 | 425781249 |
| 10 | 6425781249 |
| 11 | 36425781249 |
| 12 | 836425781249 |
| 13 | 9836425781249 |
| 14 | 19836425781249 |
| 15 | 519836425781249 |
| 16 | 2519836425781249 |
| 17 | 12519836425781249 |
| 18 | 512519836425781249 |
| 19 | 4512519836425781249 |
| 20 | 84512519836425781249 |