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 | 3 |
| 2 | 9 |
| 3 | 51 |
| 4 | 297 |
| 5 | 1731 |
| 6 | 10089 |
| 7 | 58803 |
| 8 | 342729 |
| 9 | 1997571 |
| 10 | 11642697 |
| 11 | 67858611 |
| 12 | 395508969 |
| 13 | 2305195203 |
| 14 | 13435662249 |
| 15 | 78308778291 |
| 16 | 456417007497 |
| 17 | 2660193266691 |
| 18 | 15504742592649 |
| 19 | 90368262289203 |
| 20 | 526704831142569 |
| 21 | 3069860724566211 |
| 22 | 17892459516254697 |
| 23 | 104284896372961971 |