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 | 1 |
| 3 | 8 |
| 4 | 54 |
| 5 | 584 |
| 6 | 7350 |
| 7 | 114162 |
| 8 | 2053688 |
| 9 | 42513984 |
| 10 | 991883610 |
| 11 | 25807006730 |
| 12 | 740614555692 |
| 13 | 23250961252752 |
| 14 | 792694751381078 |
| 15 | 29169262097277330 |
| 16 | 1152329533163353680 |
| 17 | 48645406703597457152 |
| 18 | 2185462919071085059890 |
| 19 | 104113841197940277430554 |
| 20 | 5242449827954998459195220 |