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 | 1 |
| 6 | 3 |
| 7 | 20 |
| 8 | 136 |
| 9 | 773 |
| 10 | 4280 |
| 11 | 22430 |
| 12 | 115097 |
| 13 | 577577 |
| 14 | 2863207 |
| 15 | 14051163 |
| 16 | 68515378 |
| 17 | 332514803 |
| 18 | 1608799915 |
| 19 | 7767857090 |
| 20 | 37460384315 |
| 21 | 180536313527 |
| 22 | 869901375049 |
| 23 | 4192038616700 |
| 24 | 20208367780744 |