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) |
|---|---|
| 1 | 0 |
| 2 | 252 |
| 3 | 4935 |
| 4 | 56560 |
| 5 | 572215 |
| 6 | 5503260 |
| 7 | 51377823 |
| 8 | 469758912 |
| 9 | 4227854463 |
| 10 | 37580958940 |
| 11 | 330712475863 |
| 12 | 2886218015856 |
| 13 | 25013889523623 |
| 14 | 215504279034492 |
| 15 | 1847179534652655 |
| 16 | 15762598695784192 |
| 17 | 133982088914258095 |
| 18 | 1134907106097349116 |
| 19 | 9583660007044397799 |
| 20 | 80704505322479268720 |