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) |
|---|---|
| 2 | 0 |
| 3 | 2 |
| 4 | 12 |
| 5 | 58 |
| 6 | 300 |
| 7 | 1682 |
| 8 | 10332 |
| 9 | 69298 |
| 10 | 505500 |
| 11 | 3990362 |
| 12 | 33925452 |
| 13 | 309248938 |
| 14 | 3010070700 |
| 15 | 31167995042 |
| 16 | 342164637372 |
| 17 | 3970297978978 |
| 18 | 48558251523900 |
| 19 | 624386836023722 |
| 20 | 8421511353298092 |
| 21 | 118891756573779418 |
| 22 | 1753452275441153100 |
| 23 | 26967372781086764402 |