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 | 0 |
| 1 | 0 |
| 2 | 1 |
| 3 | 3 |
| 4 | 10 |
| 5 | 34 |
| 6 | 118 |
| 7 | 416 |
| 8 | 1485 |
| 9 | 5355 |
| 10 | 19473 |
| 11 | 71313 |
| 12 | 262735 |
| 13 | 973027 |
| 14 | 3619955 |
| 15 | 13521307 |
| 16 | 50684778 |
| 17 | 190597594 |
| 18 | 718788034 |
| 19 | 2717755820 |
| 20 | 10300186824 |
| 21 | 39121645886 |
| 22 | 148884623768 |
| 23 | 567643844338 |
| 24 | 2167882951110 |
| 25 | 8292331115104 |