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 | 5 |
| 3 | 25 |
| 4 | 169 |
| 5 | 1361 |
| 6 | 12781 |
| 7 | 136585 |
| 8 | 1633745 |
| 9 | 21594529 |
| 10 | 312239701 |
| 11 | 4898379641 |
| 12 | 82810239865 |
| 13 | 1500015354865 |
| 14 | 28970936174909 |
| 15 | 594083320767721 |
| 16 | 12886811207794081 |
| 17 | 294742414455540545 |
| 18 | 7087332775240107685 |
| 19 | 178707496551303048409 |
| 20 | 4714241296084031285321 |
| 21 | 129830157857411005318801 |