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 | 0 |
| 4 | 0 |
| 5 | 0 |
| 6 | 1 |
| 7 | 21 |
| 8 | 266 |
| 9 | 2646 |
| 10 | 22827 |
| 11 | 179487 |
| 12 | 1323651 |
| 13 | 9321312 |
| 14 | 63436352 |
| 15 | 420693273 |
| 16 | 2734926292 |
| 17 | 17505749898 |
| 18 | 110687248392 |
| 19 | 693081601779 |
| 20 | 4306078872557 |
| 21 | 26585679462783 |
| 22 | 163305339165738 |
| 23 | 998969857983405 |