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 | 0 |
| 2 | 2 |
| 3 | 3 |
| 4 | 10 |
| 5 | 20 |
| 6 | 68 |
| 7 | 185 |
| 8 | 561 |
| 9 | 1600 |
| 10 | 4856 |
| 11 | 14490 |
| 12 | 43334 |
| 13 | 130046 |
| 14 | 390291 |
| 15 | 1172586 |
| 16 | 3523139 |
| 17 | 10593181 |
| 18 | 31854446 |
| 19 | 95807649 |
| 20 | 288198019 |
| 21 | 867005085 |
| 22 | 2608469794 |
| 23 | 7848188504 |
| 24 | 23614061363 |
| 25 | 71053102045 |
| 26 | 213798191069 |
| 27 | 643325960937 |