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 | 21 |
| 3 | 129 |
| 4 | 1029 |
| 5 | 7765 |
| 6 | 59257 |
| 7 | 450924 |
| 8 | 3435392 |
| 9 | 26160354 |
| 10 | 199243634 |
| 11 | 1517411733 |
| 12 | 11556549312 |
| 13 | 88013947545 |
| 14 | 670309228276 |
| 15 | 5105035683160 |
| 16 | 38879655193542 |
| 17 | 296105186372225 |
| 18 | 2255119850966932 |
| 19 | 17174861374796123 |
| 20 | 130802743517191075 |
| 21 | 996186073044886758 |