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 | 0 |
| 1 | 0 |
| 2 | 1 |
| 3 | 2 |
| 4 | 7 |
| 5 | 3 |
| 6 | 9 |
| 7 | 69 |
| 8 | 177 |
| 9 | 60 |
| 10 | 2715 |
| 11 | 4500 |
| 12 | 42975 |
| 13 | 104580 |
| 14 | 91665 |
| 15 | 186795 |
| 16 | 3493665 |
| 17 | 13497435 |
| 18 | 97345395 |
| 19 | 442245825 |
| 20 | 2601636975 |
| 21 | 13003053525 |
| 22 | 70985324025 |
| 23 | 64585694250 |
| 24 | 57891366225 |
| 25 | 3576632909850 |
| 26 | 9411029102475 |
| 27 | 147580842959550 |
| 28 | 476966861546175 |
| 29 | 5708173568847750 |