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 | 1 |
| 3 | 3 |
| 4 | 7 |
| 5 | 35 |
| 6 | 171 |
| 7 | 847 |
| 8 | 5041 |
| 9 | 32643 |
| 10 | 223705 |
| 11 | 1659581 |
| 12 | 13182159 |
| 13 | 110802133 |
| 14 | 984241363 |
| 15 | 9212696235 |
| 16 | 90477239521 |
| 17 | 929604133343 |
| 18 | 9969157068273 |
| 19 | 111329454692485 |
| 20 | 1291932988047775 |
| 21 | 15550838026589061 |
| 22 | 193833398512358011 |
| 23 | 2498039016973836491 |