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 | 0 |
| 2 | 2 |
| 3 | 3 |
| 4 | 13 |
| 5 | 44 |
| 6 | 156 |
| 7 | 554 |
| 8 | 1963 |
| 9 | 6964 |
| 10 | 24699 |
| 11 | 87617 |
| 12 | 310815 |
| 13 | 1102602 |
| 14 | 3911438 |
| 15 | 13875683 |
| 16 | 49223528 |
| 17 | 174618908 |
| 18 | 619455124 |
| 19 | 2197497772 |
| 20 | 7795555028 |
| 21 | 27654489341 |
| 22 | 98103442446 |
| 23 | 348018917203 |
| 24 | 1234586307769 |
| 25 | 4379656611234 |
| 26 | 15536695906316 |