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) |
|---|---|
| 3 | 1 |
| 4 | 12 |
| 5 | 77 |
| 6 | 450 |
| 7 | 2154 |
| 8 | 11592 |
| 9 | 51060 |
| 10 | 261720 |
| 11 | 1106790 |
| 12 | 5562216 |
| 13 | 23051943 |
| 14 | 114491286 |
| 15 | 468950860 |
| 16 | 2313509520 |
| 17 | 9409147640 |
| 18 | 46221336720 |
| 19 | 187136146566 |
| 20 | 916762621320 |
| 21 | 3700703183930 |
| 22 | 18096198791748 |
| 23 | 72903667955404 |
| 24 | 356052268340208 |
| 25 | 1432473805470840 |
| 26 | 6990085402419600 |
| 27 | 28096469154731484 |