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 | 0 |
| 2 | 1 |
| 3 | 1 |
| 4 | 3 |
| 5 | 8 |
| 6 | 30 |
| 7 | 145 |
| 8 | 1028 |
| 9 | 12320 |
| 10 | 274806 |
| 11 | 12007355 |
| 12 | 1019030239 |
| 13 | 165091859656 |
| 14 | 50502058492266 |
| 15 | 29054157815353374 |
| 16 | 31426486309136279775 |
| 17 | 64001015806929213894372 |
| 18 | 245935864212056913811759534 |
| 19 | 1787577725208700551275529005084 |