Generate sequential 3 bytes sequences with characters in [0-9a-z]

generate.rb

def character(i)
    return i < 10 ? (i + 48).chr : (i + 87).chr
end

def generate(n)
    i1 = n % 36
    i3 = n/(36*36)
    i2 = n/36 - i3*36
    return "#{character(i3)}#{character(i2)}#{character(i1)}"
end

# Some examples
for i in 0..50
    puts "#{i} => #{generate(i)}\n"
end

for i in 10000..10050
    puts "#{i} => #{generate(i)}\n"
end

for i in 40000..45000
    puts "#{i} => #{generate(i)}\n"
end

# Last allowed number
i = 46655 # 36*36*36 - 1
puts "#{i} => #{generate(i)}\n"

# Breaks for the next
i = 46656
puts "#{i} => #{generate(i)}\n"