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A299326
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Rectangular array by antidiagonals: row n gives the ranks of {2,3}-power towers that start with n 3's, for n >=0; see Comments.
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2
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2, 5, 7, 8, 12, 16, 11, 18, 26, 34, 14, 24, 38, 54, 70, 20, 30, 50, 78, 110, 142, 22, 42, 62, 102, 158, 222, 286, 28, 46, 86, 126, 206, 318, 446, 574, 32, 58, 94, 174, 254, 414, 638, 894, 1150, 36, 66, 118, 190, 350, 510, 830, 1278, 1790, 2302
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OFFSET
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1,1
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COMMENTS
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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.
As sequences, this one and A299325 partition the positive integers.
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REFERENCES
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1
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LINKS
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EXAMPLE
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Northwest corner:
2 5 8 11 14 20 22
7 12 18 24 30 42 46
16 26 38 50 62 86 94
34 54 78 102 126 174 190
70 110 158 206 254 350 382
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MATHEMATICA
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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 < 17, 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]
s = Select[Range[60000], Count[First[Split[t[#]]], 2] == 0 & ];
r[n_] := Select[s, Length[First[Split[t[#]]]] == n &, 12]
TableForm[Table[r[n], {n, 1, 10}]] (* A299326, array *)
w[n_, k_] := r[n][[k]];
Table[w[n - k + 1, k], {n, 10}, {k, n, 1, -1}] // Flatten (* A299326, sequence *)
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CROSSREFS
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KEYWORD
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AUTHOR
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STATUS
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approved
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