OFFSET
1,2
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))); (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.
EXAMPLE
Northwest corner:
1 2 4 5 10 11 22 23 45 48
3 7 8 9 12 15 17 18 20 21
6 14 16 19 26 29 30 33 38 40
13 28 34 39 54 57 58 69 78 80
27 56 70 79 110 113 114 141 158 160
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 = 500; g[k_] := If[EvenQ[k], {2}, {3}];
f = 6; While[f < 13, n = f; While[n < z, p = 1;
While[p < 15, 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]
r[n_] := Select[Range[30000], Max[Map[Length, Split[t[#]]]] == n & , 12];
TableForm[Table[r[n], {n, 1, 12}]] (* this array *)
w[n_, k_] := r[n][[k]];
Table[w[n - k + 1, k], {n, 12}, {k, n, 1, -1}] // Flatten (* this sequence *)
CROSSREFS
KEYWORD
AUTHOR
Clark Kimberling, Feb 08 2018
STATUS
approved