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 | 1 |
| 3 | 0 |
| 4 | 4 |
| 5 | 5 |
| 6 | 96 |
| 7 | 1057 |
| 8 | 14848 |
| 9 | 235881 |
| 10 | 4234240 |
| 11 | 84815621 |
| 12 | 1877090304 |
| 13 | 45524670061 |
| 14 | 1201345331200 |
| 15 | 34283233751145 |
| 16 | 1052350187831296 |
| 17 | 34582597023733073 |
| 18 | 1211614017182760960 |
| 19 | 45088964565749965837 |