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 | 6 |
| 3 | 24 |
| 4 | 108 |
| 5 | 406 |
| 6 | 1908 |
| 7 | 7289 |
| 8 | 34248 |
| 9 | 131766 |
| 10 | 623700 |
| 11 | 2416836 |
| 12 | 11487528 |
| 13 | 44745468 |
| 14 | 213451560 |
| 15 | 834897375 |
| 16 | 3993910416 |
| 17 | 15673923910 |
| 18 | 75152083716 |
| 19 | 295737641768 |
| 20 | 1420670333640 |
| 21 | 5603322265428 |
| 22 | 26960309526744 |
| 23 | 106539505068194 |
| 24 | 513309625743600 |
| 25 | 2031786103702780 |
| 26 | 9800639852315208 |