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 | 6 |
| 3 | 20 |
| 4 | 56 |
| 5 | 208 |
| 6 | 493 |
| 7 | 1974 |
| 8 | 4336 |
| 9 | 18258 |
| 10 | 38380 |
| 11 | 167464 |
| 12 | 342056 |
| 13 | 1532376 |
| 14 | 3067156 |
| 15 | 14022168 |
| 16 | 27646080 |
| 17 | 128438893 |
| 18 | 250291902 |
| 19 | 1178090212 |
| 20 | 2274524200 |
| 21 | 10822168448 |
| 22 | 20736353110 |
| 23 | 99564168884 |
| 24 | 189575748320 |
| 25 | 917316990660 |