151210(3)

Ruby


Number of partitions of n that do not contain 1 as a part(2)

第10 ** i 項を求めてみた。

def A002865(n)
  ps = Array.new(n + 1){0}
  ps[0] = 1
  (2..n).each{|num|
    (num..n).each{|i|
      ps[i] += ps[i - num]
    }
  }
  ps
end

(0..4).each{|i| p A002865(10 ** i)[-1]}

出力結果
0
12
21339417
933624404877723008811705095741
457349445931557250061922683900998814197008215918082809221689550699686607030908401654199943384262724122144