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) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 4 |
| 4 | 25 |
| 5 | 199 |
| 6 | 1855 |
| 7 | 19387 |
| 8 | 221407 |
| 9 | 2717782 |
| 10 | 35455981 |
| 11 | 487672243 |
| 12 | 7029980797 |
| 13 | 105732907498 |
| 14 | 1653377947393 |
| 15 | 26805765569863 |
| 16 | 449568735630517 |
| 17 | 7785116448484318 |
| 18 | 138980739891821269 |
| 19 | 2554369130466577138 |