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A063487
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Number of distinct prime divisors of 2^(2^n)-1 (A051179).
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0
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0, 1, 2, 3, 4, 5, 7, 9, 11, 13, 16, 20, 25
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OFFSET
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0,3
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COMMENTS
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2^(2^n)-1 is the product of the first n Fermat numbers F(0),...,F(n-1) (A000215). Hence this sequence is just the summation of A046052, which gives the number of prime factors in each Fermat number. - T. D. Noe, Jan 07 2003
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REFERENCES
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D. M. Burton, Elementary Number Theory, Allyn and Bacon Inc., Boston MA, 1976, p. 238.
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LINKS
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PROG
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(PARI) for(n=0, 22, print(omega(2^(2^n)-1)))
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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