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) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 2 |
| 5 | 7 |
| 6 | 28 |
| 7 | 108 |
| 8 | 414 |
| 9 | 1585 |
| 10 | 6087 |
| 11 | 23446 |
| 12 | 90532 |
| 13 | 350343 |
| 14 | 1358437 |
| 15 | 5276545 |
| 16 | 20527950 |
| 17 | 79976007 |
| 18 | 311984922 |
| 19 | 1218474389 |
| 20 | 4763911699 |
| 21 | 18643889114 |
| 22 | 73029856058 |
| 23 | 286302435505 |
| 24 | 1123267533520 |
| 25 | 4410123312095 |
| 26 | 17326303720537 |