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 | 0 |
| 2 | 0 |
| 3 | 9 |
| 4 | 156 |
| 5 | 1170 |
| 6 | 5580 |
| 7 | 19995 |
| 8 | 58824 |
| 9 | 149796 |
| 10 | 341640 |
| 11 | 714285 |
| 12 | 1391940 |
| 13 | 2559414 |
| 14 | 4482036 |
| 15 | 7529535 |
| 16 | 12204240 |
| 17 | 19173960 |
| 18 | 29309904 |
| 19 | 43730001 |
| 20 | 63847980 |
| 21 | 91428570 |
| 22 | 128649180 |
| 23 | 178168419 |
| 24 | 243201816 |
| 25 | 327605100 |
| 26 | 435965400 |
| 27 | 573700725 |
| 28 | 747168084 |