login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A299238 a(n) = the index m satisfying t(m) = 5 - t(n), where t(n) is the n-th {2,3}-power tower; see Comments. 2
2, 1, 7, 5, 4, 16, 3, 15, 12, 11, 10, 9, 34, 33, 8, 6, 32, 31, 26, 25, 24, 23, 22, 21, 20, 19, 70, 69, 68, 67, 18, 17, 14, 13, 66, 65, 64, 63, 54, 53, 52, 51, 50, 49, 48, 47, 46, 45, 44, 43, 42, 41, 40, 39, 142, 141, 140, 139, 138, 137, 136, 135, 38, 37, 36 (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 is a self-inverse permutation of the positive integers.

LINKS

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

EXAMPLE

t(12) = (3,3,2) and t(9) = (2,2,3) = 5 - (3,3,2), so that a(12) = 9.  (Note: 5 - (x(1),x(2),...,x(k)) means (5-x(1), 5-x(2),...,5-x(k)).

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]

Flatten[Table[Select[Range[1000], t[#] == 5 - t[n] &], {n, 1, 150}]] (* A299238 *)

CROSSREFS

Cf. A299229.

Sequence in context: A206533 A262057 A082791 * A342747 A077230 A244238

Adjacent sequences:  A299235 A299236 A299237 * A299239 A299240 A299241

KEYWORD

nonn,easy

AUTHOR

Clark Kimberling, Feb 07 2018

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified May 13 17:46 EDT 2021. Contains 343864 sequences. (Running on oeis4.)