def calculated_confidence score
  return 0 if score == 0
  n = score.to_f

  upvotes = score
  z = 1.281551565545 # 80% confidence
  p = upvotes.to_f / n

  left = p + (1 / (2.0 * n) * z * z)
  right = z * Math.sqrt((p * ((1.0 - p) / n)) + (z * (z / (4.0 * n * n))))
  under = 1.0 + ((1.0 / n) * z * z)

  (left - right) / under
end

lastb = -1
(0..1000).each do |n|
  c = calculated_confidence(n)
  b = (c*256).floor
  if b != lastb then
    printf "%3d %.4f %d\n", n, c, (c*256).floor
    lastb = b
  end
end

__END__
  0 0.0000 0
  1 0.3784 96
  2 0.5491 140
  3 0.6462 165
  4 0.7089 181
  5 0.7527 192
  6 0.7851 200
  7 0.8100 207
  8 0.8297 212
  9 0.8457 216
 10 0.8589 219
 11 0.8701 222
 12 0.8796 225
 13 0.8878 227
 14 0.8950 229
 15 0.9013 230
 16 0.9069 232
 17 0.9119 233
 18 0.9164 234
 19 0.9204 235
 20 0.9241 236
 21 0.9275 237
 22 0.9305 238
 24 0.9360 239
 25 0.9384 240
 27 0.9427 241
 29 0.9464 242
 31 0.9497 243
 34 0.9539 244
 37 0.9575 245
 41 0.9615 246
 46 0.9655 247
 51 0.9688 248
 59 0.9729 249
 69 0.9768 250
 83 0.9806 251
104 0.9845 252
139 0.9883 253
209 0.9922 254
419 0.9961 255