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 | 4 |
| 1 | 1 |
| 2 | 13 |
| 3 | 34 |
| 4 | 121 |
| 5 | 391 |
| 6 | 1300 |
| 7 | 4285 |
| 8 | 14161 |
| 9 | 46762 |
| 10 | 154453 |
| 11 | 510115 |
| 12 | 1684804 |
| 13 | 5564521 |
| 14 | 18378373 |
| 15 | 60699634 |
| 16 | 200477281 |
| 17 | 662131471 |
| 18 | 2186871700 |
| 19 | 7222746565 |
| 20 | 23855111401 |
| 21 | 78788080762 |
| 22 | 260219353693 |
| 23 | 859446141835 |
| 24 | 2838557779204 |
| 25 | 9375119479441 |
| 26 | 30963916217533 |