A299242 - OEIS

%I #14 Aug 07 2024 15:12:24

%S 2,7,11,12,15,16,24,26,32,33,34,38,42,46,48,49,50,52,53,54,64,65,66,

%T 67,68,69,70,78,86,94,98,100,101,102,106,108,109,110,126,130,132,133,

%U 134,136,137,138,139,140,141,142,150,154,156,157,158,166,170,172

%N Ranks of {2,3}-power towers in which #2's < #3's; see Comments.

%C Suppose that S is a set of real numbers. An S-power-tower, t, is a number t = x(1)^x(2)^...^x(k), where k >= 1 and x(i) is in S for i = 1..k. We represent t by (x(1), x(2), ..., x(k)), which for k > 1 is defined as (x(1), (x(2), ..., x(k))); (2,3,2) means 2^9. The number k is the *height* of t. If every element of S exceeds 1 and all the power towers are ranked in increasing order, the position of each in the resulting sequence is its *rank*. See A299229 for a guide to related sequences.

%C This sequence together with A299240 and A299241 partition the positive integers.

%H Clark Kimberling, <a href="/A299242/b299242.txt">Table of n, a(n) for n = 1..1000</a>

%e The first six terms are the ranks of these towers: t(2) = (3), t(7) = (3,3), t(11) = (3,2,3), t(12) = (3,3,2), t(15) = (2,3,3), t(16) = (3,3,3).

%t t[1] = {2}; t[2] = {3}; t[3] = {2, 2}; t[4] = {2, 3}; t[5] = {3, 2};

%t t[6] = {2, 2, 2}; t[7] = {3, 3}; t[8] = {3, 2, 2}; t[9] = {2, 2, 3};

%t t[10] = {2, 3, 2}; t[11] = {3, 2, 3}; t[12] = {3, 3, 2};

%t z = 190; g[k_] := If[EvenQ[k], {2}, {3}]; f = 6;

%t While[f < 13, n = f; While[n < z, p = 1;

%t   While[p < 12, m = 2 n + 1; v = t[n]; k = 0;

%t     While[k < 2^p, t[m + k] = Join[g[k], t[n + Floor[k/2]]]; k = k + 1];

%t    p = p + 1; n = m]]; f = f + 1]

%t Select[Range[1000], Count[t[#], 2] > Count[t[#], 3] &];   (* A299240 *)

%t Select[Range[1000], Count[t[#], 2] == Count[t[#], 3] &];  (* A299241 *)

%t Select[Range[1000], Count[t[#], 2] < Count[t[#], 3] &];  (* this sequence *)

%Y Cf. A299229, A299240, A299241.

%K nonn,easy

%O 1,1

%A _Clark Kimberling_, Feb 07 2018