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 | 5 |
| 3 | 55 |
| 4 | 493 |
| 5 | 3930 |
| 6 | 27207 |
| 7 | 207118 |
| 8 | 1622723 |
| 9 | 12544364 |
| 10 | 95912510 |
| 11 | 732066083 |
| 12 | 5616480627 |
| 13 | 43128778000 |
| 14 | 330817187318 |
| 15 | 2536012919124 |
| 16 | 19443866141395 |
| 17 | 149118307026576 |
| 18 | 1143608532988558 |
| 19 | 8769818352137034 |
| 20 | 67250342436670138 |
| 21 | 515711365536657077 |
| 22 | 3954797365004436075 |