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) |
|---|---|
| 4 | 1 |
| 5 | 0 |
| 6 | 0 |
| 7 | 0 |
| 8 | 0 |
| 9 | 5 |
| 10 | 56 |
| 11 | 240 |
| 12 | 620 |
| 13 | 1220 |
| 14 | 2201 |
| 15 | 4501 |
| 16 | 14231 |
| 17 | 67597 |
| 18 | 332768 |
| 19 | 1455695 |
| 20 | 5611277 |
| 21 | 19525749 |
| 22 | 63217514 |
| 23 | 197236391 |
| 24 | 617466587 |
| 25 | 2015606482 |
| 26 | 7005348816 |
| 27 | 25768091554 |
| 28 | 97973413377 |
| 29 | 375778678054 |
| 30 | 1431049415936 |
| 31 | 5374397862025 |
| 32 | 19899453137028 |
| 33 | 72900123590938 |