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 | 2 |
| 2 | 15 |
| 3 | 178 |
| 4 | 2820 |
| 5 | 55410 |
| 6 | 1294776 |
| 7 | 35003430 |
| 8 | 1073540871 |
| 9 | 36805249870 |
| 10 | 1394346324624 |
| 11 | 57831360118800 |
| 12 | 2605921998840420 |
| 13 | 126757491839620950 |
| 14 | 6619466939158637640 |
| 15 | 369368127676399990338 |
| 16 | 21932876159270004129285 |