RosettaCodeData/Task/Hofstadter-Q-sequence/Sidef/hofstadter-q-sequence-2.sidef

var Q = [0, 1, 1]
100_000.times {
    Q << (Q[-Q[-1]] + Q[-Q[-2]])
}
 
say "First 10 terms: #{Q.ft(1, 10)}"
say "Term 1000: #{Q[1000]}"
say "Terms less than preceding in first 100k: #{2..100000->count{|i|Q[i]<Q[i-1]}}"