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 | 3 |
| 4 | 15 |
| 5 | 90 |
| 6 | 629 |
| 7 | 5019 |
| 8 | 45030 |
| 9 | 448776 |
| 10 | 4919321 |
| 11 | 58825415 |
| 12 | 762089899 |
| 13 | 10633219662 |
| 14 | 158974192987 |
| 15 | 2535484008225 |
| 16 | 42970371055268 |
| 17 | 771162539117408 |
| 18 | 14609924404202130 |
| 19 | 291386317037291622 |
| 20 | 6102681801481066642 |
| 21 | 133910606028043519500 |
| 22 | 3072216586896101950757 |