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) |
|---|---|
| 1 | 1 |
| 2 | 0 |
| 3 | 5 |
| 4 | 12 |
| 5 | 51 |
| 6 | 160 |
| 7 | 585 |
| 8 | 2016 |
| 9 | 7280 |
| 10 | 26112 |
| 11 | 95325 |
| 12 | 349180 |
| 13 | 1290555 |
| 14 | 4792320 |
| 15 | 17895679 |
| 16 | 67104768 |
| 17 | 252645135 |
| 18 | 954422560 |
| 19 | 3616814565 |
| 20 | 13743842916 |
| 21 | 52357696365 |
| 22 | 199911014400 |
| 23 | 764877654105 |
| 24 | 2932030307680 |
| 25 | 11258999068416 |