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 | 4 |
| 2 | 12 |
| 3 | 44 |
| 4 | 144 |
| 5 | 528 |
| 6 | 1808 |
| 7 | 6676 |
| 8 | 23536 |
| 9 | 87568 |
| 10 | 315136 |
| 11 | 1180680 |
| 12 | 4314560 |
| 13 | 16263896 |
| 14 | 60138816 |
| 15 | 227899484 |
| 16 | 850600944 |
| 17 | 3238194560 |
| 18 | 12177384544 |
| 19 | 46542879384 |
| 20 | 176110444736 |
| 21 | 675431779856 |
| 22 | 2568878867200 |
| 23 | 9882068082112 |
| 24 | 37747540858240 |
| 25 | 145593279888736 |
| 26 | 558190182662144 |