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 | 1 |
| 2 | 1 |
| 3 | 3 |
| 4 | 11 |
| 5 | 33 |
| 6 | 82 |
| 7 | 198 |
| 8 | 516 |
| 9 | 1389 |
| 10 | 3690 |
| 11 | 9642 |
| 12 | 25143 |
| 13 | 65867 |
| 14 | 173092 |
| 15 | 454578 |
| 16 | 1192227 |
| 17 | 3125940 |
| 18 | 8198836 |
| 19 | 21509532 |
| 20 | 56429115 |
| 21 | 148023671 |
| 22 | 388279519 |
| 23 | 1018515853 |
| 24 | 2671777153 |
| 25 | 7008626377 |
| 26 | 18384947908 |
| 27 | 48227023198 |
| 28 | 126508325008 |