cp's OEIS Frontend

A168222 a(n) = A006369(A006369(n)).

%I A168222 #19 Dec 27 2024 18:51:22
%S A168222 0,1,2,3,7,9,5,6,15,4,17,10,11,23,25,13,14,31,8,33,18,19,39,41,21,22,
%T A168222 47,12,49,26,27,55,57,29,30,63,16,65,34,35,71,73,37,38,79,20,81,42,43,
%U A168222 87,89,45,46,95,24,97,50,51,103,105,53,54,111,28,113,58,59,119,121,61,62
%N A168222 a(n) = A006369(A006369(n)).
%C A168222 Inverse integer permutation to A168221;
%C A168222 a(A006368(n)) = A006369(n).
%H A168222 Paolo Xausa, <a href="/A168222/b168222.txt">Table of n, a(n) for n = 0..10000</a>
%H A168222 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a>
%H A168222 <a href="/index/3#3x1">Index entries for sequences related to 3x+1 (or Collatz) problem</a>
%F A168222 Conjectures from _Colin Barker_, Aug 15 2019: (Start)
%F A168222 G.f.: x*(1 + 2*x + 3*x^2 + 7*x^3 + 9*x^4 + 5*x^5 + 6*x^6 + 15*x^7 + 4*x^8 + 15*x^9 + 6*x^10 + 5*x^11 + 9*x^12 + 7*x^13 + 3*x^14 + 2*x^15 + x^16) / ((1 - x)^2*(1 + x + x^2)^2*(1 + x^3 + x^6)^2).
%F A168222 a(n) = 2*a(n-9) - a(n-18) for n>17.
%F A168222 (End)
%t A168222 Table[Nest[If[Divisible[#,3],2#/3,Round[4#/3]]&,n,2],{n,0,100}] (* _Paolo Xausa_, Dec 15 2023 *)
%K A168222 nonn
%O A168222 0,3
%A A168222 _Reinhard Zumkeller_, Nov 20 2009