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 | 1 |
| 2 | 1 |
| 3 | 4 |
| 4 | 12 |
| 5 | 40 |
| 6 | 116 |
| 7 | 364 |
| 8 | 1080 |
| 9 | 3276 |
| 10 | 9800 |
| 11 | 29524 |
| 12 | 88440 |
| 13 | 265720 |
| 14 | 796796 |
| 15 | 2391440 |
| 16 | 7173360 |
| 17 | 21523360 |
| 18 | 64566684 |
| 19 | 193710244 |
| 20 | 581120880 |
| 21 | 1743391832 |
| 22 | 5230147076 |
| 23 | 15690529804 |
| 24 | 47071499760 |
| 25 | 141214768200 |