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 | 1 |
| 1 | 3 |
| 2 | 18 |
| 3 | 80 |
| 4 | 400 |
| 5 | 1904 |
| 6 | 9248 |
| 7 | 44544 |
| 8 | 215296 |
| 9 | 1039104 |
| 10 | 5018112 |
| 11 | 24227840 |
| 12 | 116985856 |
| 13 | 564850688 |
| 14 | 2727354368 |
| 15 | 13168803840 |
| 16 | 63584665600 |
| 17 | 307013812224 |
| 18 | 1482394042368 |
| 19 | 7157631156224 |
| 20 | 34560101318656 |
| 21 | 166870928850944 |
| 22 | 805724122775552 |
| 23 | 3890380202311680 |
| 24 | 18784417308737536 |
| 25 | 90699190027419648 |