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 | 4 |
| 2 | 14 |
| 3 | 49 |
| 4 | 172 |
| 5 | 604 |
| 6 | 2120 |
| 7 | 7442 |
| 8 | 26124 |
| 9 | 91704 |
| 10 | 321912 |
| 11 | 1130020 |
| 12 | 3966752 |
| 13 | 13924640 |
| 14 | 48880192 |
| 15 | 171585992 |
| 16 | 602324816 |
| 17 | 2114363648 |
| 18 | 7422130912 |
| 19 | 26054187664 |
| 20 | 91459003200 |
| 21 | 321052008000 |
| 22 | 1127001041280 |
| 23 | 3956154502688 |
| 24 | 13887439208896 |
| 25 | 48749604609664 |