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 | 0 |
| 2 | 1 |
| 3 | 1 |
| 4 | 3 |
| 5 | 6 |
| 6 | 25 |
| 7 | 91 |
| 8 | 442 |
| 9 | 2241 |
| 10 | 12591 |
| 11 | 75180 |
| 12 | 478648 |
| 13 | 3211245 |
| 14 | 22635956 |
| 15 | 166828221 |
| 16 | 1281518573 |
| 17 | 10229858290 |
| 18 | 84652925554 |
| 19 | 724601312400 |
| 20 | 6403522811765 |
| 21 | 58327076550161 |
| 22 | 546764617643250 |
| 23 | 5267719312771122 |
| 24 | 52096218005705959 |
| 25 | 528285485054771639 |