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A299242 Ranks of {2,3}-power towers in which #2's < #3's; see Comments. 4
2, 7, 11, 12, 15, 16, 24, 26, 32, 33, 34, 38, 42, 46, 48, 49, 50, 52, 53, 54, 64, 65, 66, 67, 68, 69, 70, 78, 86, 94, 98, 100, 101, 102, 106, 108, 109, 110, 126, 130, 132, 133, 134, 136, 137, 138, 139, 140, 141, 142, 150, 154, 156, 157, 158, 166, 170, 172 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

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-1)); (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.

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

LINKS

Clark Kimberling, Table of n, a(n) for n = 1..1000

EXAMPLE

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).

MATHEMATICA

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

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

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

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

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

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

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

   p = p + 1; n = m]]; f = f + 1]

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

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

Select[Range[1000], Count[t[#], 2] < Count[t[#], 3] &];   (* A299242 *)

CROSSREFS

Cf. A299229, A299240, A299241.

Sequence in context: A226089 A208846 A087723 * A184792 A136998 A136734

Adjacent sequences:  A299239 A299240 A299241 * A299243 A299244 A299245

KEYWORD

nonn,easy

AUTHOR

Clark Kimberling, Feb 07 2018

STATUS

approved

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Last modified May 12 20:52 EDT 2021. Contains 343829 sequences. (Running on oeis4.)