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 | 2 |
| 3 | 5 |
| 4 | 12 |
| 5 | 72 |
| 6 | 513 |
| 7 | 4531 |
| 8 | 68662 |
| 9 | 1429824 |
| 10 | 40840428 |
| 11 | 1747979822 |
| 12 | 106711196102 |
| 13 | 9237029528023 |
| 14 | 1158315077977449 |
| 15 | 208422835867809541 |
| 16 | 53674442198900292691 |
| 17 | 19878424340459715152560 |
| 18 | 10569643478952360023168707 |