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 | 12 |
| 3 | 51 |
| 4 | 228 |
| 5 | 1035 |
| 6 | 4698 |
| 7 | 21063 |
| 8 | 92424 |
| 9 | 395091 |
| 10 | 1643790 |
| 11 | 6664383 |
| 12 | 26387100 |
| 13 | 102286587 |
| 14 | 389125506 |
| 15 | 1455994935 |
| 16 | 5368721808 |
| 17 | 19541252259 |
| 18 | 70312410774 |
| 19 | 250408115823 |
| 20 | 883617559140 |
| 21 | 3092276105163 |
| 22 | 10740749281482 |
| 23 | 37053754521831 |
| 24 | 127037475064728 |
| 25 | 433073722098675 |