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 | 8 |
| 3 | 30 |
| 4 | 138 |
| 5 | 620 |
| 6 | 3060 |
| 7 | 14910 |
| 8 | 76650 |
| 9 | 390852 |
| 10 | 2063376 |
| 11 | 10832052 |
| 12 | 58264668 |
| 13 | 312123240 |
| 14 | 1702423008 |
| 15 | 9256786110 |
| 16 | 51036229530 |
| 17 | 280696824980 |
| 18 | 1560925457520 |
| 19 | 8663089672380 |
| 20 | 48512836025940 |
| 21 | 271229902496280 |
| 22 | 1527733861191720 |
| 23 | 8593482390429300 |
| 24 | 48642125421855420 |
| 25 | 275014629509319000 |