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 | 4 |
| 2 | 28 |
| 3 | 152 |
| 4 | 744 |
| 5 | 3436 |
| 6 | 15284 |
| 7 | 66224 |
| 8 | 281424 |
| 9 | 1178196 |
| 10 | 4874444 |
| 11 | 19973192 |
| 12 | 81189688 |
| 13 | 327817404 |
| 14 | 1316035940 |
| 15 | 5257118560 |
| 16 | 20909651104 |
| 17 | 82849544868 |
| 18 | 327163551612 |
| 19 | 1288036695544 |
| 20 | 5057236343176 |
| 21 | 19807689093644 |
| 22 | 77408388584724 |