Possible bug in randomness on first call

[williamgrimes]

Can you explain this behaviour?

user> (set-random-seed! 2)
nil
user> (rand-nth (take 10 (range)))
7
user> (set-random-seed! 42) 
nil
user> (rand-nth (take 10 (range)))
7
user> (set-random-seed! 82) 
nil
user> (rand-nth (take 10 (range)))
7
user> (set-random-seed! 182)
nil
user> (rand-nth (take 10 (range)))
7
user> (set-random-seed! 1082)
nil
user> (rand-nth (take 10 (range)))
6
user> (set-random-seed! 3)
nil
user> (rand-nth (take 10 (range)))
7
user> 

Changing the seed value from 2, 3, 42, 82, 182 the first call of (rand-nth (take 10 (range))) always returns a 7? Only when I (set-random-seed! 1082) I get a different value back. Here is a further experiment, see I always get a 7 for the first element in the vector, until I set the seed to 1082

user> (set-random-seed! 1)
nil
user> (repeatedly 5 #(rand-nth (take 10 (range))))
(7 1 4 4 2)
user> (set-random-seed! 2)
nil
user> (repeatedly 5 #(rand-nth (take 10 (range))))
(7 2 9 0 4)
user> (set-random-seed! 3)
nil
user> (repeatedly 5 #(rand-nth (take 10 (range))))
(7 5 0 8 0)
user> (set-random-seed! 4)
nil
user> (repeatedly 5 #(rand-nth (take 10 (range))))
(7 9 9 8 9)
user> (set-random-seed! 5)
nil
user> (repeatedly 5 #(rand-nth (take 10 (range))))
(7 1 0 6 4)
user> (set-random-seed! 6)
nil
user> (repeatedly 5 #(rand-nth (take 10 (range))))
(7 3 5 2 7)
user> (set-random-seed! 7)
nil
user> (repeatedly 5 #(rand-nth (take 10 (range))))
(7 6 7 0 3)
user> (set-random-seed! 1082)
nil
user> (repeatedly 5 #(rand-nth (take 10 (range))))
(6 2 5 5 1)
user> 

[williamgrimes]

user> (defn rand-int-gen 
            [seed n]
            (set-random-seed! seed)
            (println "Seed: " seed " n: " n " rand-int: " (rand-int n)))
#'user/rand-int-gen
user> (map #(rand-int-gen % 5) [1 5 10 20 50 75 100 1000 10000 100000])
Seed:  1  n:  5  rand-int:  3
Seed:  5  n:  5  rand-int:  3
Seed:  10  n:  5  rand-int:  3
Seed:  20  n:  5  rand-int:  3
Seed:  50  n:  5  rand-int:  3
Seed:  75  n:  5  rand-int:  3
Seed:  100  n:  5  rand-int:  3
Seed:  1000  n:  5  rand-int:  3
Seed:  10000  n:  5  rand-int:  4
Seed:  100000  n:  5  rand-int:  2
(nil nil nil nil nil nil nil nil nil nil)

Some further experimentation applying (rand-int 5) with a range of seed values, only with a seed > 1000 does the output change?