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 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 2 |
| 5 | 6 |
| 6 | 16 |
| 7 | 36 |
| 8 | 106 |
| 9 | 442 |
| 10 | 1786 |
| 11 | 6106 |
| 12 | 23596 |
| 13 | 120836 |
| 14 | 631632 |
| 15 | 2854216 |
| 16 | 13590396 |
| 17 | 81258556 |
| 18 | 510768316 |
| 19 | 2839808572 |
| 20 | 16008902296 |
| 21 | 108643656136 |
| 22 | 787965516416 |
| 23 | 5161270717296 |
| 24 | 33513036683512 |
| 25 | 253407796702776 |
| 26 | 2065728484459576 |
| 27 | 15485032349429176 |
| 28 | 113510664648701776 |