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 | 1 |
| 2 | 4 |
| 3 | 56 |
| 4 | 299 |
| 5 | 1020 |
| 6 | 3180 |
| 7 | 3901 |
| 8 | 20944 |
| 9 | 272996 |
| 10 | 1465799 |
| 11 | 4993800 |
| 12 | 15577800 |
| 13 | 19105801 |
| 14 | 102585004 |
| 15 | 1337133056 |
| 16 | 7179484499 |
| 17 | 24459629220 |
| 18 | 76300063380 |
| 19 | 93580208101 |
| 20 | 502461329944 |
| 21 | 6549277433996 |
| 22 | 35165113611599 |
| 23 | 119803258923600 |