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 | 2 |
| 2 | 6 |
| 3 | 18 |
| 4 | 48 |
| 5 | 126 |
| 6 | 306 |
| 7 | 738 |
| 8 | 1716 |
| 9 | 3936 |
| 10 | 8862 |
| 11 | 19770 |
| 12 | 43560 |
| 13 | 95310 |
| 14 | 206874 |
| 15 | 446478 |
| 16 | 958236 |
| 17 | 2047542 |
| 18 | 4356660 |
| 19 | 9237606 |
| 20 | 19522752 |
| 21 | 41142522 |
| 22 | 86477298 |
| 23 | 181343202 |
| 24 | 379459284 |
| 25 | 792472968 |
| 26 | 1652046606 |
| 27 | 3438310428 |
| 28 | 7145039916 |
| 29 | 14826950742 |