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A014222
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a(0) = 0; thereafter a(n+1) = 3^a(n).
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12
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OFFSET
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0,3
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COMMENTS
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Alternative definition:
a(n+1) = H_4(3,n) the tetration (repeated exponentiation) of 3 times n.
For definition of and references concerning H_n(x,y) see A054871.
Next term is 12580...39387 and has 3638334640025 digits. - Shawn Ligocki (sligocki(AT)gmail.com), Oct 08 2009
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LINKS
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FORMULA
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a(n+1) = H_4(3,n) = 3^^n;
a(0) = 0, a(1) = 1, a(n+1) = 3^3^...^3 (n times).
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EXAMPLE
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a(0) = H_4(3,-1)= 0;
a(1) = H_4(3,0) = 1;
a(2) = H_4(3,1) = 3;
a(3) = H_4(3,2) = 3^3 = 27;
a(4) = H_4(3,3) = 3^3^3 = 7625597484987;
a(5) = H_4(3,4) = 3^3^3^3 = 3^7625597484987 > 10^3638334640025.
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MATHEMATICA
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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