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 | 15 |
| 6 | 60 |
| 7 | 286 |
| 8 | 1423 |
| 9 | 7185 |
| 10 | 37758 |
| 11 | 212596 |
| 12 | 1293577 |
| 13 | 8415869 |
| 14 | 57715274 |
| 15 | 414520958 |
| 16 | 3125102795 |
| 17 | 24880061105 |
| 18 | 209909409566 |
| 19 | 1871945790360 |
| 20 | 17503956383037 |
| 21 | 169851122851049 |
| 22 | 1694189515772750 |
| 23 | 17248694322541778 |
| 24 | 178473482993477591 |
| 25 | 1873036127628583885 |