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 | 3 |
| 2 | 15 |
| 3 | 77 |
| 4 | 414 |
| 5 | 2277 |
| 6 | 12727 |
| 7 | 71955 |
| 8 | 410346 |
| 9 | 2355962 |
| 10 | 13599915 |
| 11 | 78855339 |
| 12 | 458917850 |
| 13 | 2679183405 |
| 14 | 15683407785 |
| 15 | 92022516525 |
| 16 | 541050073146 |
| 17 | 3186886397310 |
| 18 | 18801598011274 |
| 19 | 111083331666918 |
| 20 | 657153430251396 |
| 21 | 3892199032434105 |
| 22 | 23077435617920925 |
| 23 | 136963282273730613 |
| 24 | 813597690808666386 |