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) |
|---|---|
| 2 | 1 |
| 3 | 4 |
| 4 | 13 |
| 5 | 40 |
| 6 | 130 |
| 7 | 472 |
| 8 | 1863 |
| 9 | 7536 |
| 10 | 30144 |
| 11 | 118420 |
| 12 | 460746 |
| 13 | 1795688 |
| 14 | 7059729 |
| 15 | 28023636 |
| 16 | 111978480 |
| 17 | 448799712 |
| 18 | 1800225540 |
| 19 | 7223348112 |
| 20 | 29006342666 |
| 21 | 116643481440 |
| 22 | 469861180529 |
| 23 | 1895748851480 |
| 24 | 7658862165738 |
| 25 | 30973386496992 |
| 26 | 125363177936450 |
| 27 | 507777786429164 |
| 28 | 2058225234116544 |