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 | 0 |
| 1 | 1 |
| 2 | 4 |
| 3 | 15 |
| 4 | 52 |
| 5 | 170 |
| 6 | 534 |
| 7 | 1631 |
| 8 | 4880 |
| 9 | 14373 |
| 10 | 41810 |
| 11 | 120406 |
| 12 | 343884 |
| 13 | 975325 |
| 14 | 2749852 |
| 15 | 7713435 |
| 16 | 21540304 |
| 17 | 59917826 |
| 18 | 166094370 |
| 19 | 458998523 |
| 20 | 1264919720 |
| 21 | 3477182961 |
| 22 | 9536877614 |
| 23 | 26102772910 |
| 24 | 71309161752 |
| 25 | 194468551225 |
| 26 | 529490287924 |