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 | 2 |
| 2 | 4 |
| 3 | 12 |
| 4 | 30 |
| 5 | 78 |
| 6 | 180 |
| 7 | 432 |
| 8 | 978 |
| 9 | 2220 |
| 10 | 4926 |
| 11 | 10908 |
| 12 | 23790 |
| 13 | 51750 |
| 14 | 111564 |
| 15 | 239604 |
| 16 | 511758 |
| 17 | 1089306 |
| 18 | 2309118 |
| 19 | 4880946 |
| 20 | 10285146 |
| 21 | 21619770 |
| 22 | 45334776 |
| 23 | 94865904 |
| 24 | 198116082 |
| 25 | 413013684 |
| 26 | 859573638 |
| 27 | 1786263822 |
| 28 | 3706729488 |
| 29 | 7681910826 |