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 | 6 |
| 2 | 21 |
| 3 | 72 |
| 4 | 225 |
| 5 | 702 |
| 6 | 2133 |
| 7 | 6480 |
| 8 | 19521 |
| 9 | 58806 |
| 10 | 176661 |
| 11 | 530712 |
| 12 | 1592865 |
| 13 | 4780782 |
| 14 | 14344533 |
| 15 | 43040160 |
| 16 | 129127041 |
| 17 | 387400806 |
| 18 | 1162222101 |
| 19 | 3486725352 |
| 20 | 10460235105 |
| 21 | 31380882462 |
| 22 | 94142824533 |
| 23 | 282429005040 |
| 24 | 847287546561 |