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 | 6 |
| 2 | 21 |
| 3 | 69 |
| 4 | 219 |
| 5 | 679 |
| 6 | 2070 |
| 7 | 6235 |
| 8 | 18608 |
| 9 | 55148 |
| 10 | 162532 |
| 11 | 476857 |
| 12 | 1393903 |
| 13 | 4061917 |
| 14 | 11805549 |
| 15 | 34234268 |
| 16 | 99079243 |
| 17 | 286255570 |
| 18 | 825770674 |
| 19 | 2378862529 |
| 20 | 6844519217 |
| 21 | 19671211354 |
| 22 | 56477811098 |
| 23 | 162002541976 |
| 24 | 464298401040 |
| 25 | 1329640943422 |