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 | 1 |
| 2 | 1 |
| 3 | 5 |
| 4 | 20 |
| 5 | 104 |
| 6 | 546 |
| 7 | 3066 |
| 8 | 17655 |
| 9 | 104555 |
| 10 | 630773 |
| 11 | 3867617 |
| 12 | 24020932 |
| 13 | 150827740 |
| 14 | 955808680 |
| 15 | 6105327912 |
| 16 | 39268000188 |
| 17 | 254093573088 |
| 18 | 1652984379150 |
| 19 | 10804631902350 |
| 20 | 70925539707330 |
| 21 | 467373389649870 |
| 22 | 3090558380977020 |
| 23 | 20501504119375500 |
| 24 | 136392970090612950 |