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 | 1 |
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 1 |
| 6 | 1 |
| 7 | 2 |
| 8 | 6 |
| 9 | 16 |
| 10 | 60 |
| 11 | 266 |
| 12 | 1547 |
| 13 | 10786 |
| 14 | 88193 |
| 15 | 805579 |
| 16 | 8037796 |
| 17 | 86223660 |
| 18 | 985883873 |
| 19 | 11946592242 |
| 20 | 152808993767 |
| 21 | 2056701139136 |
| 22 | 29051369533596 |
| 23 | 429669276147047 |
| 24 | 6640178380127244 |
| 25 | 107026751932268789 |
| 26 | 1796103830404560857 |
| 27 | 31334029441145918974 |
| 28 | 567437704731717802783 |