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 | 3 |
| 3 | 12 |
| 4 | 61 |
| 5 | 380 |
| 6 | 2815 |
| 7 | 24213 |
| 8 | 237348 |
| 9 | 2612681 |
| 10 | 31915787 |
| 11 | 428481472 |
| 12 | 6271362282 |
| 13 | 99388642292 |
| 14 | 1695614865711 |
| 15 | 30984649882928 |
| 16 | 603790447393402 |
| 17 | 12498732438500663 |
| 18 | 273902239550757626 |
| 19 | 6334968666307580051 |
| 20 | 154211723833861061644 |
| 21 | 3941258052200287007636 |