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 | 4 |
| 1 | 14 |
| 2 | 64 |
| 3 | 344 |
| 4 | 1984 |
| 5 | 11744 |
| 6 | 70144 |
| 7 | 420224 |
| 8 | 2520064 |
| 9 | 15117824 |
| 10 | 90701824 |
| 11 | 544200704 |
| 12 | 3265183744 |
| 13 | 19591061504 |
| 14 | 117546287104 |
| 15 | 705277558784 |
| 16 | 4231665025024 |
| 17 | 25389989494784 |
| 18 | 152339935657984 |
| 19 | 914039611326464 |
| 20 | 5484237662715904 |