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 | 18 |
| 2 | 150 |
| 3 | 980 |
| 4 | 5670 |
| 5 | 30492 |
| 6 | 156156 |
| 7 | 772200 |
| 8 | 3719430 |
| 9 | 17551820 |
| 10 | 81477396 |
| 11 | 373173528 |
| 12 | 1690097500 |
| 13 | 7582037400 |
| 14 | 33738060600 |
| 15 | 149067936720 |
| 16 | 654576544710 |
| 17 | 2858667619500 |
| 18 | 12423860225700 |
| 19 | 53760146239800 |
| 20 | 231720014946420 |
| 21 | 995238809839560 |
| 22 | 4260800401533000 |