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 | 9 |
| 2 | 61 |
| 3 | 429 |
| 4 | 3011 |
| 5 | 21141 |
| 6 | 148433 |
| 7 | 1042167 |
| 8 | 7317185 |
| 9 | 51374875 |
| 10 | 360709449 |
| 11 | 2532586341 |
| 12 | 17781606753 |
| 13 | 124846894103 |
| 14 | 876565722303 |
| 15 | 6154478019155 |
| 16 | 43211363078111 |
| 17 | 303392406838867 |
| 18 | 2130156189729353 |
| 19 | 14956094122197975 |