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 | 1 |
| 2 | 3 |
| 3 | 9 |
| 4 | 31 |
| 5 | 121 |
| 6 | 523 |
| 7 | 2469 |
| 8 | 12611 |
| 9 | 69161 |
| 10 | 404663 |
| 11 | 2512769 |
| 12 | 16485691 |
| 13 | 113842301 |
| 14 | 824723643 |
| 15 | 6249805129 |
| 16 | 49416246911 |
| 17 | 406754704841 |
| 18 | 3478340425563 |
| 19 | 30845565317189 |
| 20 | 283187362333331 |
| 21 | 2687568043654521 |
| 22 | 26329932233283223 |
| 23 | 265946395403810289 |
| 24 | 2766211109503317451 |