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 | 0 |
| 2 | 0 |
| 3 | 9 |
| 4 | 18 |
| 5 | 189 |
| 6 | 360 |
| 7 | 2799 |
| 8 | 5238 |
| 9 | 36189 |
| 10 | 67140 |
| 11 | 435699 |
| 12 | 804258 |
| 13 | 5021289 |
| 14 | 9238320 |
| 15 | 56191599 |
| 16 | 103144878 |
| 17 | 615724389 |
| 18 | 1128303900 |
| 19 | 6641519499 |
| 20 | 12154735098 |
| 21 | 70773675489 |
| 22 | 129392615880 |
| 23 | 746963079399 |
| 24 | 1364533542918 |
| 25 | 7822667714589 |