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 | 2 |
| 3 | 6 |
| 4 | 24 |
| 5 | 119 |
| 6 | 694 |
| 7 | 4580 |
| 8 | 33249 |
| 9 | 260092 |
| 10 | 2159381 |
| 11 | 18815124 |
| 12 | 170605392 |
| 13 | 1599499163 |
| 14 | 15427796984 |
| 15 | 152487271455 |
| 16 | 1539554179950 |
| 17 | 15836801521762 |
| 18 | 165625811815111 |
| 19 | 1757953168747511 |
| 20 | 18908510233855411 |
| 21 | 205838673911323648 |
| 22 | 2265393020812413370 |
| 23 | 25182471016157568626 |