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 | 2 |
| 2 | 5 |
| 3 | 20 |
| 4 | 77 |
| 5 | 306 |
| 6 | 1209 |
| 7 | 4656 |
| 8 | 17713 |
| 9 | 66618 |
| 10 | 248025 |
| 11 | 916020 |
| 12 | 3359789 |
| 13 | 12250026 |
| 14 | 44435997 |
| 15 | 160466304 |
| 16 | 577185745 |
| 17 | 2068826290 |
| 18 | 7392167585 |
| 19 | 26338879556 |
| 20 | 93609302941 |
| 21 | 331924381218 |
| 22 | 1174482354493 |
| 23 | 4147807582672 |
| 24 | 14622567051025 |
| 25 | 51466158436298 |
| 26 | 180869949252245 |
| 27 | 634753692067716 |