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 | 0 |
| 1 | 1 |
| 2 | 0 |
| 3 | 5 |
| 4 | 4 |
| 5 | 33 |
| 6 | 56 |
| 7 | 253 |
| 8 | 588 |
| 9 | 2105 |
| 10 | 5632 |
| 11 | 18261 |
| 12 | 52052 |
| 13 | 161617 |
| 14 | 473928 |
| 15 | 1443629 |
| 16 | 4287196 |
| 17 | 12948969 |
| 18 | 38672144 |
| 19 | 116365957 |
| 20 | 348398820 |
| 21 | 1046594561 |
| 22 | 3136987480 |
| 23 | 9416554845 |
| 24 | 28238479724 |
| 25 | 84737808793 |
| 26 | 254168687136 |
| 27 | 762595539893 |