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) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 12 |
| 3 | 57 |
| 4 | 264 |
| 5 | 1261 |
| 6 | 6141 |
| 7 | 30276 |
| 8 | 150853 |
| 9 | 758145 |
| 10 | 3836896 |
| 11 | 19534086 |
| 12 | 99957904 |
| 13 | 513756551 |
| 14 | 2650822585 |
| 15 | 13724435509 |
| 16 | 71275344341 |
| 17 | 371177285715 |
| 18 | 1937791196448 |
| 19 | 10139548682524 |
| 20 | 53165765660928 |
| 21 | 279301910804937 |