150607(2)

Ruby


Mian-Chowla sequence

オンライン整数列大辞典の
A005282（http://oeis.org/A005282/list）
と比較し、答え合わせしてみる。

N = 50

ary = [1]

s_ary = [2]

m = 2

while ary.size < N

  s_ary0 = []

  size = 0

  ary.each{|i|

    j = m + i

    break if s_ary.include?(j)

    s_ary0.push(j)

    size += 1

  }

  if size == ary.size

    j = m + m

    if !s_ary.include?(j)

      s_ary0.push(j)

      # m以下のs_aryの要素は以後使わないので、除いておく

      s_ary = (s_ary + s_ary0).select{|k| k > m}

      ary.push(m)

    end

  end

  m += 1

end

# OEIS A005282のデータ

ary0 =

[1,2,4,8,13,21,31,45,66,81,97,123,148,182,204,252,

 290,361,401,475,565,593,662,775,822,916,970,1016,

 1159,1312,1395,1523,1572,1821,1896,2029,2254,2379,

 2510,2780,2925,3155,3354,3591,3797,3998,4297,4433,

 4779,4851]

# 一致の確認

p ary == ary0