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Search: id:A059269
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| A059269 |
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Number of divisors d(n) is divisible by 3. |
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+0
3
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| 4, 9, 12, 18, 20, 25, 28, 32, 36, 44, 45, 49, 50, 52, 60, 63, 68, 72, 75, 76, 84, 90, 92, 96, 98, 99, 100, 108, 116, 117, 121, 124, 126, 132, 140, 144, 147, 148, 150, 153, 156, 160, 164, 169, 171, 172, 175, 180, 188, 196, 198, 200, 204, 207, 212, 220, 224, 225, 228
(list; graph; listen)
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OFFSET
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0,1
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COMMENT
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d(n) is divisible by 3 iff at least one prime in the prime factorization of n has exponent of the form 3*m + 2. This sequence is an extension of the sequence A038109 in which the numbers has at least one prime with exponent 2 (the case of m = 0 here ) in their prime factorization.
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EXAMPLE
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a(7) = 28 because the number of divisors of 28 d(28) = 6
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MAPLE
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with(numtheory): for n from 1 to 1000 do if tau(n) mod 3 = 0 then printf(`%d, `, n) fi: od:
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CROSSREFS
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A038109, A000005.
Sequence in context: A034018 A047461 A089910 this_sequence A081619 A038109 A067259
Adjacent sequences: A059266 A059267 A059268 this_sequence A059270 A059271 A059272
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KEYWORD
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nonn,easy
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AUTHOR
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Avi Peretz (njk(AT)netvision.net.il), Jan 24 2001
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EXTENSIONS
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More terms from James A. Sellers (sellersj(AT)math.psu.edu), Jan 24 2001
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