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 | 1 |
| 3 | 5 |
| 4 | 21 |
| 5 | 86 |
| 6 | 355 |
| 7 | 1488 |
| 8 | 6335 |
| 9 | 27352 |
| 10 | 119547 |
| 11 | 528045 |
| 12 | 2353791 |
| 13 | 10575810 |
| 14 | 47849685 |
| 15 | 217824285 |
| 16 | 996999525 |
| 17 | 4585548680 |
| 18 | 21182609875 |
| 19 | 98236853415 |
| 20 | 457211008415 |
| 21 | 2134851575050 |
| 22 | 9997848660345 |
| 23 | 46949087361550 |
| 24 | 221022160284101 |
| 25 | 1042916456739696 |
| 26 | 4931673470809525 |
| 27 | 23367060132453323 |