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) |
|---|---|
| 0 | 1 |
| 1 | 4 |
| 2 | 22 |
| 3 | 130 |
| 4 | 794 |
| 5 | 4944 |
| 6 | 31180 |
| 7 | 198440 |
| 8 | 1271626 |
| 9 | 8192524 |
| 10 | 53009102 |
| 11 | 344212906 |
| 12 | 2241812648 |
| 13 | 14637774688 |
| 14 | 95786202688 |
| 15 | 628002401520 |
| 16 | 4124304597834 |
| 17 | 27126202533252 |
| 18 | 178651732923346 |
| 19 | 1178005033926998 |
| 20 | 7776048412324714 |