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 | 0 |
| 1 | 2 |
| 2 | 4 |
| 3 | 18 |
| 4 | 60 |
| 5 | 242 |
| 6 | 924 |
| 7 | 3698 |
| 8 | 14620 |
| 9 | 58482 |
| 10 | 233244 |
| 11 | 932978 |
| 12 | 3729180 |
| 13 | 14916722 |
| 14 | 59655964 |
| 15 | 238623858 |
| 16 | 954451740 |
| 17 | 3817806962 |
| 18 | 15271053084 |
| 19 | 61084212338 |
| 20 | 244336150300 |
| 21 | 977344601202 |
| 22 | 3909375608604 |