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) |
|---|---|
| 4 | 1 |
| 5 | 11 |
| 6 | 78 |
| 7 | 455 |
| 8 | 2380 |
| 9 | 11628 |
| 10 | 54264 |
| 11 | 245157 |
| 12 | 1081575 |
| 13 | 4686825 |
| 14 | 20030010 |
| 15 | 84672315 |
| 16 | 354817320 |
| 17 | 1476337800 |
| 18 | 6107086800 |
| 19 | 25140840660 |
| 20 | 103077446706 |
| 21 | 421171648758 |
| 22 | 1715884494940 |
| 23 | 6973199770790 |
| 24 | 28277527346376 |
| 25 | 114456658306760 |
| 26 | 462525733568080 |
| 27 | 1866442158555975 |