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 | 3 |
| 3 | 20 |
| 4 | 175 |
| 5 | 2016 |
| 6 | 28182 |
| 7 | 465036 |
| 8 | 8828820 |
| 9 | 189496450 |
| 10 | 4535113154 |
| 11 | 119706872376 |
| 12 | 3454013050488 |
| 13 | 108140144894600 |
| 14 | 3650830138093500 |
| 15 | 132194177662402800 |
| 16 | 5110163818369981650 |
| 17 | 210037720563156731850 |
| 18 | 9146299175093615073000 |
| 19 | 420627290039763259876500 |