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 | 7 |
| 2 | 35 |
| 3 | 140 |
| 4 | 490 |
| 5 | 1554 |
| 6 | 4578 |
| 7 | 12720 |
| 8 | 33705 |
| 9 | 85855 |
| 10 | 211519 |
| 11 | 506408 |
| 12 | 1182650 |
| 13 | 2702350 |
| 14 | 6056850 |
| 15 | 13343820 |
| 16 | 28947240 |
| 17 | 61926900 |
| 18 | 130814600 |
| 19 | 273163100 |
| 20 | 564415390 |
| 21 | 1154933230 |
| 22 | 2342193350 |
| 23 | 4710707400 |
| 24 | 9401674275 |
| 25 | 18629923053 |
| 26 | 36670044621 |
| 27 | 71728832280 |
| 28 | 139485074370 |