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) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 20 |
| 5 | 70 |
| 6 | 252 |
| 7 | 924 |
| 8 | 3432 |
| 9 | 12870 |
| 10 | 48619 |
| 11 | 184735 |
| 12 | 705222 |
| 13 | 2702609 |
| 14 | 10390940 |
| 15 | 40062132 |
| 16 | 154830696 |
| 17 | 599641425 |
| 18 | 2326640877 |
| 19 | 9042327525 |
| 20 | 35194002709 |
| 21 | 137160956815 |
| 22 | 535193552973 |
| 23 | 2090558951396 |
| 24 | 8174176541450 |
| 25 | 31990402045260 |
| 26 | 125301956523471 |
| 27 | 491168514123342 |