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 | 0 |
| 2 | 0 |
| 3 | 3 |
| 4 | 50 |
| 5 | 472 |
| 6 | 3253 |
| 7 | 18435 |
| 8 | 91028 |
| 9 | 404154 |
| 10 | 1646000 |
| 11 | 6232542 |
| 12 | 22151853 |
| 13 | 74433912 |
| 14 | 237790084 |
| 15 | 725557353 |
| 16 | 2122652633 |
| 17 | 5973816190 |
| 18 | 16219720273 |
| 19 | 42595011951 |
| 20 | 108438121237 |
| 21 | 268160583493 |
| 22 | 645345542877 |
| 23 | 1513887056435 |