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) |
|---|---|
| 1 | 3 |
| 2 | 21 |
| 3 | 231 |
| 4 | 385 |
| 5 | 7315 |
| 6 | 168245 |
| 7 | 4542615 |
| 8 | 140821065 |
| 9 | 28164213 |
| 10 | 366134769 |
| 11 | 15743795067 |
| 12 | 739958368149 |
| 13 | 12579292258533 |
| 14 | 62896461292665 |
| 15 | 3710891216267235 |
| 16 | 3710891216267235 |
| 17 | 248629711489904745 |
| 18 | 17652709515783236895 |
| 19 | 88263547578916184475 |
| 20 | 6972820258734378573525 |