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 | 0 |
| 2 | 5 |
| 3 | 45 |
| 4 | 245 |
| 5 | 1305 |
| 6 | 6605 |
| 7 | 33405 |
| 8 | 167405 |
| 9 | 838845 |
| 10 | 4196045 |
| 11 | 20989245 |
| 12 | 104955245 |
| 13 | 524820945 |
| 14 | 2624149445 |
| 15 | 13120970445 |
| 16 | 65605075445 |
| 17 | 328026491505 |
| 18 | 1640133571805 |
| 19 | 8200673428605 |
| 20 | 41003372712605 |
| 21 | 205016891401905 |
| 22 | 1025084484848405 |
| 23 | 5125422563427405 |