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A101081
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Number of distinct prime factors of (prime p concatenated p times).
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3
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2, 2, 3, 3, 6, 6, 6, 3, 6, 8, 5, 7, 7, 8, 6, 6, 6, 10, 5, 5, 7, 10, 10, 9, 7, 7, 8, 11, 9, 8, 9, 14, 8
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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LINKS
| Dario Alejandro Alpern, Factorization using the Elliptic Curve Method.
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EXAMPLE
| The number of distinct prime factors of 22 is 2.
The number of distinct prime factors of 333 is 2.
The number of distinct prime factors of 55555 is 3.
Then the number of distinct prime factors of 7777777 is 3.
a(16) comes from 53 * 107 * 1659431 * 1325815267337711173 * 47198858799491425660200071 * 9090909090909090909090909090909090909090909090909091. a(17) comes from 59 * 1889 * 2559647034361 * 1090805842068098677837 * 4411922770996074109644535362851087 * 4340876285657460212144534289928559826755746751. a(18) comes from 61 * 733 * 4637 * 81131 * 329401 * 974293 * 1360682471 * 106007173861643 * 7061709990156159479 * 11205222530116836855321528257890437575145023592596037161. Concerning a(19) = 67*(100^67-1)/99 = 67 * 493121 * 79863595778924342083 * 25648528130160606364784685146362888405160909090909090909090909090911655761903925151545569377605545379749607 (C107). - Robert G. Wilson v (rgwv(AT)rgwv.com), Jan 27 2005
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MATHEMATICA
| f[n_] := Length[ FactorInteger[ FromDigits[ Flatten[ Table[ IntegerDigits[ Prime[n]], {Prime[n]}] ]]]]; Table[ f[n], {n, 15}] (from Robert G. Wilson v Jan 27 2005)
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CROSSREFS
| Cf. A101459.
Sequence in context: A196055 A145787 A096111 * A147795 A038716 A168659
Adjacent sequences: A101078 A101079 A101080 * A101082 A101083 A101084
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KEYWORD
| nonn,base
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AUTHOR
| Parthasarathy Nambi (PachaNambi(AT)yahoo.com), Jan 21 2005
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EXTENSIONS
| a(11)-a(15) from Ray Chandler (rayjchandler(AT)sbcglobal.net), Jan 25 2005
a(16)-a(18) from Robert G. Wilson v (rgwv(AT)rgwv.com), Jan 27 2005
Corrected and extended to a(33) by D. S. McNeil (mcneil(AT)hku.hk), Jan 07 2011
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