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) |
|---|---|
| 1 | 1 |
| 2 | 5 |
| 3 | 22 |
| 4 | 105 |
| 5 | 511 |
| 6 | 2534 |
| 7 | 12720 |
| 8 | 64449 |
| 9 | 328900 |
| 10 | 1688115 |
| 11 | 8705060 |
| 12 | 45064110 |
| 13 | 234054198 |
| 14 | 1219053680 |
| 15 | 6364813192 |
| 16 | 33302104593 |
| 17 | 174570695175 |
| 18 | 916628799380 |
| 19 | 4820160541350 |
| 20 | 25381091113455 |
| 21 | 133808636072595 |
| 22 | 706211862466500 |
| 23 | 3730964595817680 |
| 24 | 19729042153581150 |