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 | 0 |
| 4 | 9 |
| 5 | 48 |
| 6 | 200 |
| 7 | 780 |
| 8 | 2989 |
| 9 | 11424 |
| 10 | 43740 |
| 11 | 167940 |
| 12 | 646624 |
| 13 | 2496120 |
| 14 | 9657674 |
| 15 | 37442132 |
| 16 | 145422645 |
| 17 | 565722688 |
| 18 | 2203961396 |
| 19 | 8597496564 |
| 20 | 33578000572 |
| 21 | 131282408360 |
| 22 | 513791607378 |
| 23 | 2012616400036 |
| 24 | 7890371113904 |
| 25 | 30957699535728 |