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 | 4 |
| 1 | 15 |
| 2 | 67 |
| 3 | 322 |
| 4 | 1657 |
| 5 | 9089 |
| 6 | 52922 |
| 7 | 325869 |
| 8 | 2114719 |
| 9 | 14418716 |
| 10 | 103004851 |
| 11 | 769052061 |
| 12 | 5987339748 |
| 13 | 48506099635 |
| 14 | 408157244967 |
| 15 | 3561086589202 |
| 16 | 32164670915029 |
| 17 | 300324194090773 |
| 18 | 2894932531218482 |
| 19 | 28773297907499129 |