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 | 30 |
| 3 | 155 |
| 4 | 855 |
| 5 | 4305 |
| 6 | 23255 |
| 7 | 116705 |
| 8 | 614655 |
| 9 | 3108355 |
| 10 | 16168430 |
| 11 | 81136755 |
| 12 | 422279580 |
| 13 | 2116775030 |
| 14 | 10893334980 |
| 15 | 54857686305 |
| 16 | 281413208380 |
| 17 | 1410806289330 |
| 18 | 7237582729155 |
| 19 | 36262232611605 |
| 20 | 185184341144805 |