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 | 12 |
| 6 | 78 |
| 7 | 376 |
| 8 | 1509 |
| 9 | 5340 |
| 10 | 17234 |
| 11 | 51796 |
| 12 | 147054 |
| 13 | 398388 |
| 14 | 1037560 |
| 15 | 2612520 |
| 16 | 6387965 |
| 17 | 15221412 |
| 18 | 35446980 |
| 19 | 80865304 |
| 20 | 181076216 |
| 21 | 398660292 |
| 22 | 864186408 |
| 23 | 1846759404 |
| 24 | 3894731430 |
| 25 | 8113669352 |
| 26 | 16710519860 |
| 27 | 34049851236 |
| 28 | 68687627812 |
| 29 | 137257430140 |
| 30 | 271842916654 |