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 | 20 |
| 2 | 230 |
| 3 | 1960 |
| 4 | 13685 |
| 5 | 82524 |
| 6 | 443870 |
| 7 | 2175800 |
| 8 | 9869990 |
| 9 | 41907380 |
| 10 | 168012824 |
| 11 | 640438680 |
| 12 | 2334121995 |
| 13 | 8171039800 |
| 14 | 27580783270 |
| 15 | 90058003200 |
| 16 | 285253928790 |
| 17 | 878572253720 |
| 18 | 2636748302650 |
| 19 | 7725084195240 |
| 20 | 22130265931900 |
| 21 | 62079251390180 |