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 | 0 |
| 2 | 1 |
| 3 | 0 |
| 4 | 4 |
| 5 | 14 |
| 6 | 102 |
| 7 | 682 |
| 8 | 5484 |
| 9 | 49288 |
| 10 | 492812 |
| 11 | 5418154 |
| 12 | 64993966 |
| 13 | 844658714 |
| 14 | 11822116868 |
| 15 | 177292309424 |
| 16 | 2836140479376 |
| 17 | 48206588630826 |
| 18 | 867597809813018 |
| 19 | 16482372327022854 |
| 20 | 329612875955466784 |
| 21 | 6921235129197714036 |
| 22 | 152254880756288024536 |
| 23 | 3501612401180417830334 |
| 24 | 84033374067657870984810 |
| 25 | 2100715696249652623708150 |