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 | 3 |
| 2 | 10 |
| 3 | 60 |
| 4 | 470 |
| 5 | 4344 |
| 6 | 45320 |
| 7 | 521200 |
| 8 | 6513280 |
| 9 | 87613440 |
| 10 | 1260188800 |
| 11 | 19286781440 |
| 12 | 312884243840 |
| 13 | 5363632995840 |
| 14 | 96904980170240 |
| 15 | 1840977689943040 |
| 16 | 36700487712701440 |
| 17 | 766296476640215040 |
| 18 | 16728728381231472640 |