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 | 4 |
| 3 | 34 |
| 4 | 416 |
| 5 | 6319 |
| 6 | 111124 |
| 7 | 2177346 |
| 8 | 46440184 |
| 9 | 1061938195 |
| 10 | 25762345804 |
| 11 | 658072997702 |
| 12 | 17600573291712 |
| 13 | 490770914734054 |
| 14 | 14219015899154068 |
| 15 | 426904437068035200 |
| 16 | 13252855203929697200 |
| 17 | 424634035832800883743 |
| 18 | 14020984603588221319072 |
| 19 | 476460483567807053745450 |