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 | 5 |
| 2 | 35 |
| 3 | 305 |
| 4 | 3105 |
| 5 | 35505 |
| 6 | 444225 |
| 7 | 5970725 |
| 8 | 85068365 |
| 9 | 1272022745 |
| 10 | 19810304695 |
| 11 | 319422093325 |
| 12 | 5307057746125 |
| 13 | 90508769121165 |
| 14 | 1579462112057595 |
| 15 | 28130401719357645 |
| 16 | 510199561574590125 |
| 17 | 9405815167297415025 |
| 18 | 175977472926360962295 |
| 19 | 3336795660732459377085 |
| 20 | 64047222901288457886285 |