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 | 1 |
| 3 | 7 |
| 4 | 14 |
| 5 | 41 |
| 6 | 103 |
| 7 | 274 |
| 8 | 713 |
| 9 | 1871 |
| 10 | 4894 |
| 11 | 12817 |
| 12 | 33551 |
| 13 | 87842 |
| 14 | 229969 |
| 15 | 602071 |
| 16 | 1576238 |
| 17 | 4126649 |
| 18 | 10803703 |
| 19 | 28284466 |
| 20 | 74049689 |
| 21 | 193864607 |
| 22 | 507544126 |
| 23 | 1328767777 |
| 24 | 3478759199 |
| 25 | 9107509826 |
| 26 | 23843770273 |
| 27 | 62423800999 |
| 28 | 163427632718 |
| 29 | 427859097161 |
| 30 | 1120149658759 |