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 | 10 |
| 3 | 32 |
| 4 | 110 |
| 5 | 392 |
| 6 | 1428 |
| 7 | 5280 |
| 8 | 19734 |
| 9 | 74360 |
| 10 | 281996 |
| 11 | 1074944 |
| 12 | 4115020 |
| 13 | 15808912 |
| 14 | 60917800 |
| 15 | 235350720 |
| 16 | 911315430 |
| 17 | 3535767000 |
| 18 | 13742347740 |
| 19 | 53495534400 |
| 20 | 208537056420 |
| 21 | 813950932080 |
| 22 | 3180614712600 |
| 23 | 12441628655040 |