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 | 1 |
| 2 | 2 |
| 3 | 14 |
| 4 | 48 |
| 5 | 224 |
| 6 | 880 |
| 7 | 3760 |
| 8 | 15360 |
| 9 | 64192 |
| 10 | 265088 |
| 11 | 1101440 |
| 12 | 4561920 |
| 13 | 18925568 |
| 14 | 78447616 |
| 15 | 325313536 |
| 16 | 1348730880 |
| 17 | 5592420352 |
| 18 | 23187169280 |
| 19 | 96141172736 |
| 20 | 398624489472 |
| 21 | 1652807303168 |
| 22 | 6852965761024 |
| 23 | 28414229807104 |
| 24 | 117812861337600 |
| 25 | 488483370827776 |