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 | 1 |
| 2 | 4 |
| 3 | 13 |
| 4 | 42 |
| 5 | 131 |
| 6 | 402 |
| 7 | 1218 |
| 8 | 3657 |
| 9 | 10899 |
| 10 | 32298 |
| 11 | 95257 |
| 12 | 279844 |
| 13 | 819390 |
| 14 | 2392392 |
| 15 | 6967956 |
| 16 | 20250974 |
| 17 | 58744089 |
| 18 | 170118980 |
| 19 | 491913999 |
| 20 | 1420493862 |
| 21 | 4096940530 |
| 22 | 11803172152 |
| 23 | 33970257473 |
| 24 | 97678027311 |
| 25 | 280624328431 |
| 26 | 805587723862 |