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 | 4 |
| 3 | 5 |
| 4 | 21 |
| 5 | 49 |
| 6 | 176 |
| 7 | 513 |
| 8 | 1720 |
| 9 | 5401 |
| 10 | 17777 |
| 11 | 57421 |
| 12 | 188657 |
| 13 | 617177 |
| 14 | 2033176 |
| 15 | 6697745 |
| 16 | 22139781 |
| 17 | 73262233 |
| 18 | 242931322 |
| 19 | 806516561 |
| 20 | 2681475049 |
| 21 | 8925158441 |
| 22 | 29740390673 |
| 23 | 99196158145 |
| 24 | 331163178476 |
| 25 | 1106489052969 |
| 26 | 3699881730901 |
| 27 | 12380449027325 |
| 28 | 41454579098853 |