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 | 1 |
| 2 | 1 |
| 3 | 5 |
| 4 | 33 |
| 5 | 230 |
| 6 | 1827 |
| 7 | 15466 |
| 8 | 137085 |
| 9 | 1260545 |
| 10 | 11930690 |
| 11 | 115607310 |
| 12 | 1142333751 |
| 13 | 11475243990 |
| 14 | 116910923720 |
| 15 | 1205717972880 |
| 16 | 12567935262965 |
| 17 | 132238934938755 |
| 18 | 1403053736656275 |
| 19 | 14997682223032473 |
| 20 | 161392162120990570 |
| 21 | 1747309339397241620 |
| 22 | 19021521745371642498 |