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 | 1 |
| 2 | 1 |
| 3 | 4 |
| 4 | 13 |
| 5 | 31 |
| 6 | 82 |
| 7 | 253 |
| 8 | 757 |
| 9 | 2173 |
| 10 | 6341 |
| 11 | 18888 |
| 12 | 56266 |
| 13 | 167324 |
| 14 | 499773 |
| 15 | 1499059 |
| 16 | 4503557 |
| 17 | 13546893 |
| 18 | 40824379 |
| 19 | 123233868 |
| 20 | 372472353 |
| 21 | 1127080252 |
| 22 | 3414310032 |
| 23 | 10353722919 |
| 24 | 31425764410 |
| 25 | 95463814056 |
| 26 | 290222666436 |
| 27 | 882954212908 |
| 28 | 2688037654049 |
| 29 | 8188468874808 |