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 | 2 |
| 1 | 9 |
| 2 | 32 |
| 3 | 115 |
| 4 | 420 |
| 5 | 1554 |
| 6 | 5808 |
| 7 | 21879 |
| 8 | 82940 |
| 9 | 316030 |
| 10 | 1209312 |
| 11 | 4644094 |
| 12 | 17889032 |
| 13 | 69089700 |
| 14 | 267444000 |
| 15 | 1037348415 |
| 16 | 4030774380 |
| 17 | 15687019590 |
| 18 | 61137753600 |
| 19 | 238580530650 |
| 20 | 932105099640 |
| 21 | 3645473785980 |
| 22 | 14271279927840 |
| 23 | 55918717024950 |
| 24 | 219283705045080 |
| 25 | 860564513057004 |
| 26 | 3379592965275968 |