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 | 3 |
| 2 | 13 |
| 3 | 67 |
| 4 | 397 |
| 5 | 2627 |
| 6 | 19085 |
| 7 | 150339 |
| 8 | 1272205 |
| 9 | 11481155 |
| 10 | 109852813 |
| 11 | 1109011779 |
| 12 | 11765211021 |
| 13 | 130707706435 |
| 14 | 1516160466573 |
| 15 | 18314760232771 |
| 16 | 229865470694797 |
| 17 | 2991427959247939 |
| 18 | 40292570823959693 |
| 19 | 560791503840522563 |
| 20 | 8053114165521427341 |
| 21 | 119158887402348541507 |