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 | 1 |
| 4 | 5 |
| 5 | 23 |
| 6 | 98 |
| 7 | 405 |
| 8 | 1644 |
| 9 | 6604 |
| 10 | 26356 |
| 11 | 104746 |
| 12 | 415155 |
| 13 | 1642493 |
| 14 | 6490622 |
| 15 | 25629581 |
| 16 | 101156936 |
| 17 | 399151400 |
| 18 | 1574818496 |
| 19 | 6213255614 |
| 20 | 24515233082 |
| 21 | 96739530062 |
| 22 | 381803092580 |
| 23 | 1507141137026 |
| 24 | 5950525214360 |
| 25 | 23498966702808 |