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 | 2 |
| 3 | 6 |
| 4 | 33 |
| 5 | 231 |
| 6 | 2046 |
| 7 | 20460 |
| 8 | 225360 |
| 9 | 3040650 |
| 10 | 42562410 |
| 11 | 663200340 |
| 12 | 14604306060 |
| 13 | 310211542410 |
| 14 | 6204234151200 |
| 15 | 163322250505200 |
| 16 | 4256423144450400 |
| 17 | 134630366022322500 |
| 18 | 3634363143602406600 |
| 19 | 134462435323300144200 |
| 20 | 4233013654405404511500 |