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 | 3 |
| 2 | 19 |
| 3 | 117 |
| 4 | 771 |
| 5 | 5193 |
| 6 | 35629 |
| 7 | 247467 |
| 8 | 1734931 |
| 9 | 12250953 |
| 10 | 87006249 |
| 11 | 620818047 |
| 12 | 4447016781 |
| 13 | 31959556983 |
| 14 | 230331965379 |
| 15 | 1664043517557 |
| 16 | 12047551338771 |
| 17 | 87387014213433 |
| 18 | 634918255153369 |
| 19 | 4619923954541247 |
| 20 | 33661450900419001 |