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 | 2 |
| 4 | 5 |
| 5 | 11 |
| 6 | 32 |
| 7 | 88 |
| 8 | 315 |
| 9 | 1134 |
| 10 | 4691 |
| 11 | 19838 |
| 12 | 88467 |
| 13 | 399679 |
| 14 | 1839857 |
| 15 | 8533474 |
| 16 | 39893579 |
| 17 | 187393549 |
| 18 | 884152226 |
| 19 | 4185740194 |
| 20 | 19876589828 |
| 21 | 94633345517 |
| 22 | 451615299593 |
| 23 | 2159769331316 |
| 24 | 10348546459872 |
| 25 | 49672000435712 |
| 26 | 238804870806677 |
| 27 | 1149792978953236 |
| 28 | 5543621480301561 |