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A363746
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Initial digit of the decimal expansion of the tetration n^^n (in Don Knuth's up-arrow notation).
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1
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OFFSET
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0,3
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COMMENTS
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a(5), the most significant digit of the tetration 5^^5, has been estimated to be equal to 1 (and this is also consistent with Benford's law), but there is not any strict proof at the present time and computers are not powerful enough to calculate it without uncertainty.
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LINKS
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FORMULA
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a(n) = floor(n^^n/10^floor(log_10(n^^n))).
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EXAMPLE
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a(3) = 7 since 3^^3 = 7625597484987.
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CROSSREFS
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KEYWORD
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base,hard,more,nonn
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AUTHOR
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STATUS
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approved
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