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 | 5 |
| 3 | 27 |
| 4 | 171 |
| 5 | 1077 |
| 6 | 6963 |
| 7 | 45523 |
| 8 | 300417 |
| 9 | 1995897 |
| 10 | 13332697 |
| 11 | 89461271 |
| 12 | 602525231 |
| 13 | 4070925653 |
| 14 | 27580062519 |
| 15 | 187294750351 |
| 16 | 1274550544383 |
| 17 | 8689294370837 |
| 18 | 59336253329567 |
| 19 | 405779196651853 |
| 20 | 2778627840692687 |
| 21 | 19049684072515863 |