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 | 4 |
| 1 | 16 |
| 2 | 80 |
| 3 | 496 |
| 4 | 3536 |
| 5 | 26992 |
| 6 | 212048 |
| 7 | 1684720 |
| 8 | 13442768 |
| 9 | 107437168 |
| 10 | 859182416 |
| 11 | 6872514544 |
| 12 | 54977282000 |
| 13 | 439809752944 |
| 14 | 3518452514384 |
| 15 | 28147543587568 |
| 16 | 225180119118032 |
| 17 | 1801440264196720 |
| 18 | 14411520047331152 |
| 19 | 115292154179921392 |
| 20 | 922337214843187664 |
| 21 | 7378697662956950896 |
| 22 | 59029581136289955920 |
| 23 | 472236648588222693616 |