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 | 5 |
| 3 | 35 |
| 4 | 324 |
| 5 | 3744 |
| 6 | 51902 |
| 7 | 839362 |
| 8 | 15513096 |
| 9 | 322550616 |
| 10 | 7451677632 |
| 11 | 189366303840 |
| 12 | 5249764639248 |
| 13 | 157666361452560 |
| 14 | 5099445234111888 |
| 15 | 176713626295062384 |
| 16 | 6531995374500741888 |
| 17 | 256537368987293878272 |
| 18 | 10667901271715707803264 |
| 19 | 468261481657502075856768 |
| 20 | 21635865693957558515860224 |