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 | 3 |
| 2 | 10 |
| 3 | 34 |
| 4 | 116 |
| 5 | 396 |
| 6 | 1352 |
| 7 | 4616 |
| 8 | 15760 |
| 9 | 53808 |
| 10 | 183712 |
| 11 | 627232 |
| 12 | 2141504 |
| 13 | 7311552 |
| 14 | 24963200 |
| 15 | 85229696 |
| 16 | 290992384 |
| 17 | 993510144 |
| 18 | 3392055808 |
| 19 | 11581202944 |
| 20 | 39540700160 |
| 21 | 135000394752 |
| 22 | 460920178688 |
| 23 | 1573679925248 |
| 24 | 5372879343616 |
| 25 | 18344157523968 |
| 26 | 62630871408640 |
| 27 | 213835170586624 |