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 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 0 |
| 6 | 0 |
| 7 | 0 |
| 8 | 0 |
| 9 | 1 |
| 10 | 18 |
| 11 | 261 |
| 12 | 3420 |
| 13 | 42300 |
| 14 | 504000 |
| 15 | 5850000 |
| 16 | 66600000 |
| 17 | 747000000 |
| 18 | 8280000000 |
| 19 | 90899999991 |
| 20 | 989999999757 |
| 21 | 10709999995383 |
| 22 | 115199999925399 |
| 23 | 1232999998904070 |
| 24 | 13139999984885400 |
| 25 | 139499999800740000 |
| 26 | 1475999997460650000 |
| 27 | 15569999968482900000 |