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 | 2 |
| 3 | 6 |
| 4 | 24 |
| 5 | 120 |
| 6 | 720 |
| 7 | 5040 |
| 8 | 40320 |
| 9 | 362880 |
| 10 | 2943360 |
| 11 | 21898800 |
| 12 | 152622000 |
| 13 | 1017952680 |
| 14 | 6623303544 |
| 15 | 42700751022 |
| 16 | 276054834902 |
| 17 | 1805409270031 |
| 18 | 12020754177001 |
| 19 | 80930279045116 |
| 20 | 548117873866228 |
| 21 | 3720269813727312 |
| 22 | 25239622338694272 |
| 23 | 170893063638209664 |