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 | 81 |
| 3 | 279 |
| 4 | 961 |
| 5 | 4743 |
| 6 | 23409 |
| 7 | 100215 |
| 8 | 429025 |
| 9 | 1942075 |
| 10 | 8791225 |
| 11 | 38933415 |
| 12 | 172423161 |
| 13 | 770225067 |
| 14 | 3440643649 |
| 15 | 15317395695 |
| 16 | 68191488225 |
| 17 | 303989603715 |
| 18 | 1355149763881 |
| 19 | 6037892299063 |
| 20 | 26901929503849 |
| 21 | 119887169037291 |