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 | 3 |
| 3 | 6 |
| 4 | 24 |
| 5 | 98 |
| 6 | 240 |
| 7 | 878 |
| 8 | 13104 |
| 9 | 34560 |
| 10 | 143840 |
| 11 | 1628640 |
| 12 | 4421376 |
| 13 | 27644438 |
| 14 | 291751956 |
| 15 | 1666163520 |
| 16 | 10523628456 |
| 17 | 216625138884 |
| 18 | 779556556800 |
| 19 | 5873176163328 |
| 20 | 107021765366544 |
| 21 | 633207380826720 |
| 22 | 6399554302310400 |
| 23 | 66975753492138600 |
| 24 | 594616643557427040 |