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 | 0 |
| 2 | 15 |
| 3 | 110 |
| 4 | 605 |
| 5 | 3100 |
| 6 | 15595 |
| 7 | 78090 |
| 8 | 390585 |
| 9 | 1953080 |
| 10 | 9765575 |
| 11 | 48828070 |
| 12 | 244140565 |
| 13 | 1220703060 |
| 14 | 6103515555 |
| 15 | 30517578050 |
| 16 | 152587890545 |
| 17 | 762939453040 |
| 18 | 3814697265535 |
| 19 | 19073486328030 |
| 20 | 95367431640525 |
| 21 | 476837158203020 |
| 22 | 2384185791015515 |
| 23 | 11920928955078010 |
| 24 | 59604644775390505 |
| 25 | 298023223876953000 |