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 | 3 |
| 3 | 6 |
| 4 | 15 |
| 5 | 36 |
| 6 | 99 |
| 7 | 270 |
| 8 | 783 |
| 9 | 2298 |
| 10 | 6936 |
| 11 | 21204 |
| 12 | 65895 |
| 13 | 206862 |
| 14 | 656253 |
| 15 | 2098602 |
| 16 | 6761028 |
| 17 | 21917364 |
| 18 | 71450229 |
| 19 | 234070806 |
| 20 | 770216253 |
| 21 | 2544458592 |
| 22 | 8435990916 |
| 23 | 28060099692 |
| 24 | 93612265143 |
| 25 | 313153860210 |
| 26 | 1050194570445 |
| 27 | 3530080085868 |