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 | 4581 |
| 8 | 33287 |
| 9 | 260967 |
| 10 | 2175379 |
| 11 | 19072271 |
| 12 | 174426353 |
| 13 | 1653484169 |
| 14 | 16165513608 |
| 15 | 162344264849 |
| 16 | 1669261805697 |
| 17 | 17526017429722 |
| 18 | 187472773174466 |
| 19 | 2039233971499931 |
| 20 | 22520066337196663 |
| 21 | 252141732452056894 |
| 22 | 2858721279079666465 |
| 23 | 32786666580814894741 |