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 | 2 |
| 2 | 5 |
| 3 | 13 |
| 4 | 39 |
| 5 | 139 |
| 6 | 587 |
| 7 | 2897 |
| 8 | 16462 |
| 9 | 106301 |
| 10 | 771313 |
| 11 | 6228073 |
| 12 | 55494336 |
| 13 | 541651873 |
| 14 | 5753940704 |
| 15 | 66147591142 |
| 16 | 818802488476 |
| 17 | 10864622564915 |
| 18 | 153914784829775 |
| 19 | 2319599022540318 |
| 20 | 37068215129072522 |
| 21 | 626279667948552452 |