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 | 1 |
| 3 | 2 |
| 4 | 7 |
| 5 | 23 |
| 6 | 72 |
| 7 | 238 |
| 8 | 831 |
| 9 | 2959 |
| 10 | 10645 |
| 11 | 38824 |
| 12 | 143492 |
| 13 | 535700 |
| 14 | 2016020 |
| 15 | 7641574 |
| 16 | 29152015 |
| 17 | 111841263 |
| 18 | 431209723 |
| 19 | 1669945778 |
| 20 | 6493144143 |
| 21 | 25338440143 |
| 22 | 99204579648 |
| 23 | 389570145288 |
| 24 | 1534026813892 |
| 25 | 6055885764548 |
| 26 | 23962654178012 |
| 27 | 95023123291680 |