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 | 21 |
| 3 | 131 |
| 4 | 830 |
| 5 | 5066 |
| 6 | 30456 |
| 7 | 179256 |
| 8 | 1038593 |
| 9 | 5928071 |
| 10 | 33402561 |
| 11 | 186021335 |
| 12 | 1025162709 |
| 13 | 5596047683 |
| 14 | 30282832593 |
| 15 | 162573152651 |
| 16 | 866385400935 |
| 17 | 4585861723905 |
| 18 | 24120596727003 |
| 19 | 126124094912499 |
| 20 | 655868112470175 |
| 21 | 3393060517486981 |
| 22 | 17468543071082489 |