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Search: id:A101081
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| A101081 |
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Number of distinct prime factors of (prime p concatenated p times). |
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+0
4
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| 2, 2, 3, 3, 6, 6, 6, 3, 6, 8, 5, 7, 7, 8, 6, 6, 10
(list; graph; listen)
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OFFSET
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1,1
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LINKS
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Dario Alejandro Alpern, Factorization using the Elliptic Curve Method.
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EXAMPLE
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If p=2, then the number of distinct prime factors of 22 is 2.
If p=3, then the number of distinct prime factors of 333 is 2.
If p=5, then the number of distinct prime factors of 55555 is 3.
If p=7, 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
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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
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Cf. A101459.
Sequence in context: A116417 A145787 A096111 this_sequence A147795 A038716 A035642
Adjacent sequences: A101078 A101079 A101080 this_sequence A101082 A101083 A101084
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KEYWORD
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nonn
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AUTHOR
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Parthasarathy Nambi (PachaNambi(AT)yahoo.com), Jan 21 2005
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EXTENSIONS
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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
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