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) |
|---|---|
| 1 | 2 |
| 2 | 7 |
| 3 | 28 |
| 4 | 129 |
| 5 | 630 |
| 6 | 3131 |
| 7 | 15632 |
| 8 | 78133 |
| 9 | 390634 |
| 10 | 1953135 |
| 11 | 9765636 |
| 12 | 48828137 |
| 13 | 244140638 |
| 14 | 1220703139 |
| 15 | 6103515640 |
| 16 | 30517578141 |
| 17 | 152587890642 |
| 18 | 762939453143 |
| 19 | 3814697265644 |
| 20 | 19073486328145 |
| 21 | 95367431640646 |
| 22 | 476837158203147 |
| 23 | 2384185791015648 |
| 24 | 11920928955078149 |
| 25 | 59604644775390650 |