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 | 0 |
| 1 | 1 |
| 2 | 3 |
| 3 | 8 |
| 4 | 26 |
| 5 | 94 |
| 6 | 406 |
| 7 | 1896 |
| 8 | 10440 |
| 9 | 59472 |
| 10 | 405264 |
| 11 | 2673648 |
| 12 | 22396128 |
| 13 | 160828368 |
| 14 | 1704287568 |
| 15 | 11993279232 |
| 16 | 177349981824 |
| 17 | 957018589056 |
| 18 | 25766036316288 |
| 19 | 33555346603776 |
| 20 | 5403108443855616 |
| 21 | -28811285794990080 |
| 22 | 1643455634670489600 |
| 23 | -21001090458387594240 |
| 24 | 692074413969784289280 |