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 | 19 |
| 4 | 153 |
| 5 | 1561 |
| 6 | 19563 |
| 7 | 289339 |
| 8 | 4932273 |
| 9 | 95258161 |
| 10 | 2055639123 |
| 11 | 49019157859 |
| 12 | 1280056939593 |
| 13 | 36329281202761 |
| 14 | 1113449691889083 |
| 15 | 36651273215389579 |
| 16 | 1289577677407798113 |
| 17 | 48299079453732363361 |
| 18 | 1918528841276621473443 |
| 19 | 80559757274836073592499 |