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 | 0 |
| 1 | 1 |
| 2 | 3 |
| 3 | 11 |
| 4 | 43 |
| 5 | 180 |
| 6 | 790 |
| 7 | 3590 |
| 8 | 16745 |
| 9 | 79705 |
| 10 | 385615 |
| 11 | 1890747 |
| 12 | 9375216 |
| 13 | 46931897 |
| 14 | 236873261 |
| 15 | 1204089630 |
| 16 | 6159064015 |
| 17 | 31678706490 |
| 18 | 163739008070 |
| 19 | 850051218980 |
| 20 | 4430529313065 |
| 21 | 23175017046351 |
| 22 | 121617754070653 |
| 23 | 640122809255716 |
| 24 | 3378402106118508 |
| 25 | 17875011275340275 |