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 | 2 |
| 3 | 9 |
| 4 | 28 |
| 5 | 145 |
| 6 | 726 |
| 7 | 4249 |
| 8 | 27000 |
| 9 | 186561 |
| 10 | 1387450 |
| 11 | 11034001 |
| 12 | 93295236 |
| 13 | 834720913 |
| 14 | 7870851366 |
| 15 | 77943848025 |
| 16 | 808159323376 |
| 17 | 8749874083585 |
| 18 | 98687599614450 |
| 19 | 1157060036429857 |
| 20 | 14075106913366140 |
| 21 | 177337182574590801 |
| 22 | 2310567819180310558 |
| 23 | 31087556340427928617 |