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 | 6 |
| 3 | 50 |
| 4 | 490 |
| 5 | 5292 |
| 6 | 60984 |
| 7 | 736164 |
| 8 | 9202050 |
| 9 | 118195220 |
| 10 | 1551580888 |
| 11 | 20734762776 |
| 12 | 281248448936 |
| 13 | 3863302870000 |
| 14 | 53644719852000 |
| 15 | 751920156592200 |
| 16 | 10626401036545650 |
| 17 | 151269944167296900 |
| 18 | 2167317913508055000 |