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 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 1 |
| 5 | 4 |
| 6 | 24 |
| 7 | 47 |
| 8 | 153 |
| 9 | 669 |
| 10 | 5628 |
| 11 | 13554 |
| 12 | 61747 |
| 13 | 247170 |
| 14 | 1539565 |
| 15 | 16979571 |
| 16 | 53166394 |
| 17 | 268393296 |
| 18 | 1382097160 |
| 19 | 7831424654 |
| 20 | 59720804940 |
| 21 | 917256305956 |
| 22 | 3326800474687 |
| 23 | 20441030261195 |
| 24 | 112690616749302 |
| 25 | 773175024537549 |
| 26 | 5164903931159843 |
| 27 | 52976603588044961 |