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 | 1 |
| 1 | 0 |
| 2 | 3 |
| 3 | 3 |
| 4 | 24 |
| 5 | 54 |
| 6 | 283 |
| 7 | 900 |
| 8 | 4098 |
| 9 | 15286 |
| 10 | 66555 |
| 11 | 268173 |
| 12 | 1156951 |
| 13 | 4852722 |
| 14 | 21007605 |
| 15 | 90167059 |
| 16 | 393152058 |
| 17 | 1712432070 |
| 18 | 7524092134 |
| 19 | 33112353060 |
| 20 | 146518404963 |
| 21 | 649861681966 |
| 22 | 2893369443183 |
| 23 | 12913307575722 |
| 24 | 57800647230933 |
| 25 | 259298148600504 |
| 26 | 1165967972216967 |