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 | 0 |
| 2 | 1 |
| 3 | 1 |
| 4 | 3 |
| 5 | 6 |
| 6 | 16 |
| 7 | 43 |
| 8 | 121 |
| 9 | 365 |
| 10 | 1155 |
| 11 | 3832 |
| 12 | 13274 |
| 13 | 47862 |
| 14 | 179084 |
| 15 | 693589 |
| 16 | 2774358 |
| 17 | 11438972 |
| 18 | 48531450 |
| 19 | 211543687 |
| 20 | 946052129 |
| 21 | 4335355493 |
| 22 | 20334619731 |
| 23 | 97521410321 |
| 24 | 477755388567 |
| 25 | 2388776942837 |
| 26 | 12180420245150 |
| 27 | 63291320166423 |
| 28 | 334906186618646 |
| 29 | 1803525009870353 |