cp's OEIS Frontend

A290566 Coefficients in 5-adic expansion of 2^(1/3).

%I A290566 #18 Oct 24 2018 02:33:12
%S A290566 3,0,2,2,3,1,4,0,2,3,0,0,4,0,4,4,3,1,1,2,0,0,2,4,0,0,2,1,4,2,2,4,0,4,
%T A290566 2,3,1,2,3,0,0,2,0,3,4,4,2,3,2,0,4,1,2,2,3,3,0,4,2,2,3,4,4,3,4,0,2,1,
%U A290566 2,3,4,4,2,3,3,0,3,4,1,3,1,0,2,2,1,4,4,1
%N A290566 Coefficients in 5-adic expansion of 2^(1/3).
%H A290566 Seiichi Manyama, <a href="/A290566/b290566.txt">Table of n, a(n) for n = 0..10000</a>
%o A290566 (Ruby)
%o A290566 require 'OpenSSL'
%o A290566 def f_a(ary, a)
%o A290566   (0..ary.size - 1).inject(0){|s, i| s + ary[i] * a ** i}
%o A290566 end
%o A290566 def df(ary)
%o A290566   (1..ary.size - 1).map{|i| i * ary[i]}
%o A290566 end
%o A290566 def A(c_ary, k, m, n)
%o A290566   x = OpenSSL::BN.new((-f_a(df(c_ary), k)).to_s).mod_inverse(m).to_i % m
%o A290566   f_ary = c_ary.map{|i| x * i}
%o A290566   f_ary[1] += 1
%o A290566   d_ary = []
%o A290566   ary = [0]
%o A290566   a, mod = k, m
%o A290566   (n + 1).times{|i|
%o A290566     b = a % mod
%o A290566     d_ary << (b - ary[-1]) / m ** i
%o A290566     ary << b
%o A290566     a = f_a(f_ary, b)
%o A290566     mod *= m
%o A290566   }
%o A290566   d_ary
%o A290566 end
%o A290566 def A290566(n)
%o A290566   A([-2, 0, 0, 1], 3, 5, n)
%o A290566 end
%o A290566 p A290566(100)
%o A290566 (PARI) Vecrev( digits( truncate( (2+O(5^100))^(1/3) ), 5) ) \\ _Joerg Arndt_, Aug 06 2017
%Y A290566 Cf. A290563, A290567.
%K A290566 nonn
%O A290566 0,1
%A A290566 _Seiichi Manyama_, Aug 06 2017