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 | 1 |
| 2 | -1 |
| 3 | 0 |
| 4 | 1 |
| 5 | 1 |
| 6 | 4 |
| 7 | -10 |
| 8 | -4 |
| 9 | 9 |
| 10 | -1 |
| 11 | -44 |
| 12 | 75 |
| 13 | 224 |
| 14 | -299 |
| 15 | -180 |
| 16 | 225 |
| 17 | 1 |
| 18 | 408 |
| 19 | 92 |
| 20 | -7400 |
| 21 | 4758 |
| 22 | 19592 |
| 23 | -15876 |
| 24 | -12600 |
| 25 | 11025 |
| 26 | -1 |
| 27 | -3688 |
| 28 | -23387 |
| 29 | 194160 |
| 30 | 155702 |
| 31 | -1313312 |
| 32 | 264586 |
| 33 | 2445840 |
| 34 | -1289925 |
| 35 | -1323000 |
| 36 | 893025 |
| 37 | 1 |
| 38 | 33212 |
| 39 | 804210 |
| 40 | -3980044 |
| 41 | -20402105 |
| 42 | 64915224 |
| 43 | 74573980 |
| 44 | -279362392 |
| 45 | -18229761 |
| 46 | 414859500 |
| 47 | -144802350 |
| 48 | -196465500 |
| 49 | 108056025 |
| 50 | -1 |
| 51 | -298932 |
| 52 | -22347185 |
| 53 | 33998224 |
| 54 | 1349961795 |
| 55 | -1942776004 |
| 56 | -12484642765 |
| 57 | 21458573952 |
| 58 | 32679754381 |
| 59 | -72263858940 |
| 60 | -19224079875 |
| 61 | 92046754800 |
| 62 | -20560114575 |
| 63 | -39332393100 |
| 64 | 18261468225 |
| 65 | 1 |
| 66 | 2690416 |
| 67 | 581249144 |
| 68 | 2783246128 |
| 69 | -71371497796 |
| 70 | -59230867280 |
| 71 | 1313526021896 |
| 72 | -606679979408 |
| 73 | -7350770598874 |
| 74 | 7512502827344 |
| 75 | 15289334428104 |
| 76 | -22529210886000 |
| 77 | -9997446759300 |
| 78 | 25906255174800 |
| 79 | -3292683193800 |
| 80 | -10226422206000 |
| 81 | 4108830350625 |