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 | 7 |
| 1 | 28 |
| 2 | 140 |
| 3 | 784 |
| 4 | 4676 |
| 5 | 29008 |
| 6 | 184820 |
| 7 | 1200304 |
| 8 | 7907396 |
| 9 | 52666768 |
| 10 | 353815700 |
| 11 | 2393325424 |
| 12 | 16279522916 |
| 13 | 111239118928 |
| 14 | 762963987380 |
| 15 | 5249352196144 |
| 16 | 36210966447236 |
| 17 | 250337422025488 |
| 18 | 1733857359003860 |
| 19 | 12027604452404464 |
| 20 | 83544895168776356 |
| 21 | 580964060390826448 |