A randomness question
You look at what is supposed to be two different series of random numbers, between 1 and 13. One of the series has the string 1,2,3,4,5,6,7,8,9,10,11,12,13 buried somewhere in it, the second does not. What can you conclude?
If the series are long enough, you can conclude that the second is _not_ random, because the sequence 1..13 is expected to happen every so often. The first series looks perfectly random so long as the sequential pattern doesn't happen significantly more frequently that probability theory predicts. One well-known random number generator test is the "poker test" which works about like you would think. Generate numbers from 1-52, representing the 52 different cards in a deck. The various "hands" dealt, summed over a large number of tests, ought to match the known probabilities for similar poker hands... Not match exactly of course, as this is about a normal distribution, but match within reason, say via any one of several types of statistical tests that determine whether a series of observed data are within reason...
If there were no clumps, the deck would most certainly not be random...