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 | 0 |
| 1 | 0 |
| 2 | 4 |
| 3 | 28 |
| 4 | 124 |
| 5 | 532 |
| 6 | 2164 |
| 7 | 8788 |
| 8 | 35284 |
| 9 | 141628 |
| 10 | 567004 |
| 11 | 2269948 |
| 12 | 9081724 |
| 13 | 36334492 |
| 14 | 145345564 |
| 15 | 581412508 |
| 16 | 2325680284 |
| 17 | 9302841652 |
| 18 | 37211487124 |
| 19 | 148846430068 |
| 20 | 595386201844 |
| 21 | 2381546731732 |
| 22 | 9526188851284 |
| 23 | 38104763100628 |
| 24 | 152419060098004 |
| 25 | 609676271166388 |
| 26 | 2438705115439924 |
| 27 | 9754820584849588 |