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 | 15 |
| 2 | 105 |
| 3 | 532 |
| 4 | 2241 |
| 5 | 8361 |
| 6 | 28610 |
| 7 | 91740 |
| 8 | 279624 |
| 9 | 818272 |
| 10 | 2315712 |
| 11 | 6372480 |
| 12 | 17123840 |
| 13 | 45082368 |
| 14 | 116596224 |
| 15 | 296879104 |
| 16 | 745543680 |
| 17 | 1849344000 |
| 18 | 4536958976 |
| 19 | 11020075008 |
| 20 | 26526547968 |
| 21 | 63329075200 |
| 22 | 150057123840 |