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 | 12 |
| 2 | 90 |
| 3 | 544 |
| 4 | 2823 |
| 5 | 13116 |
| 6 | 55982 |
| 7 | 222936 |
| 8 | 838011 |
| 9 | 2998896 |
| 10 | 10282986 |
| 11 | 33959016 |
| 12 | 108458924 |
| 13 | 336141084 |
| 14 | 1013801700 |
| 15 | 2982628712 |
| 16 | 8577246237 |
| 17 | 24152726184 |
| 18 | 66699488360 |
| 19 | 180885417408 |
| 20 | 482312100000 |
| 21 | 1265779076680 |
| 22 | 3272696917782 |
| 23 | 8343402502128 |
| 24 | 20989675199987 |
| 25 | 52143220175940 |