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 | 4 |
| 2 | 36 |
| 3 | 234 |
| 4 | 1534 |
| 5 | 10291 |
| 6 | 68613 |
| 7 | 457178 |
| 8 | 3048314 |
| 9 | 20323497 |
| 10 | 135493938 |
| 11 | 903332290 |
| 12 | 6022478907 |
| 13 | 40151569213 |
| 14 | 267688593389 |
| 15 | 1784667144371 |
| 16 | 11898290761269 |
| 17 | 79325337411332 |
| 18 | 528858244821419 |
| 19 | 3525872716944031 |
| 20 | 23506825387232109 |