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 | 21 |
| 3 | 364 |
| 4 | 2730 |
| 5 | 13020 |
| 6 | 46655 |
| 7 | 137256 |
| 8 | 349524 |
| 9 | 797160 |
| 10 | 1666665 |
| 11 | 3247860 |
| 12 | 5971966 |
| 13 | 10458084 |
| 14 | 17568915 |
| 15 | 28476560 |
| 16 | 44739240 |
| 17 | 68389776 |
| 18 | 102036669 |
| 19 | 148978620 |
| 20 | 213333330 |
| 21 | 300181420 |
| 22 | 415726311 |
| 23 | 567470904 |
| 24 | 764411900 |
| 25 | 1017252600 |