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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
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,3
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COMMENTS
| 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 (noe(AT)sspectra.com), Jan 07 2003
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REFERENCES
| D. M. Burton, Elementary Number Theory, Allyn and Bacon Inc., Boston MA, 1976, p. 238.
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LINKS
| Eric Weisstein's World of Mathematics, Fermat Number
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PROG
| (PARI) for(n=0, 22, print(omega(2^(2^n)-1)))
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CROSSREFS
| Cf. A051179, A000215, A046052.
Sequence in context: A158923 A008740 A089651 * A081998 A074583 A001092
Adjacent sequences: A063484 A063485 A063486 * A063488 A063489 A063490
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KEYWORD
| nonn
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AUTHOR
| Jason Earls (zevi_35711(AT)yahoo.com), Jul 28 2001
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EXTENSIONS
| More terms from T. D. Noe (noe(AT)sspectra.com), Jan 07 2003
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