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 | 3 |
| 1 | 21 |
| 2 | 147 |
| 3 | 1029 |
| 4 | 7203 |
| 5 | 50421 |
| 6 | 352947 |
| 7 | 2470629 |
| 8 | 17294403 |
| 9 | 121060821 |
| 10 | 847425747 |
| 11 | 5931980229 |
| 12 | 41523861603 |
| 13 | 290667031221 |
| 14 | 2034669218547 |
| 15 | 14242684529829 |
| 16 | 99698791708803 |
| 17 | 697891541961621 |
| 18 | 4885240793731347 |
| 19 | 34196685556119429 |
| 20 | 239376798892836003 |
| 21 | 1675637592249852021 |