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 | 4 |
| 3 | 12 |
| 4 | 36 |
| 5 | 132 |
| 6 | 396 |
| 7 | 1716 |
| 8 | 5148 |
| 9 | 25740 |
| 10 | 87516 |
| 11 | 437580 |
| 12 | 1662804 |
| 13 | 8314020 |
| 14 | 38244492 |
| 15 | 167943204 |
| 16 | 839716020 |
| 17 | 3862693692 |
| 18 | 17298150012 |
| 19 | 86490750060 |
| 20 | 397857450276 |
| 21 | 1850902051284 |
| 22 | 9254510256420 |
| 23 | 42570747179532 |
| 24 | 201748323589956 |
| 25 | 1008741617949780 |
| 26 | 4640211442568988 |