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Search: id:A109422
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| A109422 |
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Numbers n such that tau(n)/bigomega(n) is not an integer [tau(n) =number of divisors of n; bigomega(n)=number of prime divisors of n, counted with multiplicities]. |
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+0
2
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| 4, 8, 9, 16, 25, 27, 30, 32, 36, 42, 49, 64, 66, 70, 72, 78, 81, 100, 102, 105, 108, 110, 114, 120, 121, 125, 128, 130, 138, 144, 154, 165, 168, 169, 170, 174, 180, 182, 186, 190, 195, 196, 200, 216, 222, 225, 230, 231, 238, 240, 243, 246, 252, 255, 256, 258
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OFFSET
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1,1
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COMMENT
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Integers greater than 1 and not in A109421.
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EXAMPLE
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16 is in the sequence because tau(16)=5 (1,2,4,8,16) and bigomega(16)=4 (2,2,2,2) and so tau(16)/bigomega(16)=5/4.
12 is not in the sequence because tau(12)=6 (1,2,3,4,6,12) and bigomega(12)=3 (2,2,3) and so tau(12)/bigomega(12)=2
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MAPLE
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with(numtheory): b:=proc(n) if type(tau(n)/bigomega(n), integer)=false then n else fi end: seq(b(n), n=2..300);
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CROSSREFS
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Complement of A109421.
Sequence in context: A100657 A140104 A127398 this_sequence A158804 A080366 A001694
Adjacent sequences: A109419 A109420 A109421 this_sequence A109423 A109424 A109425
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KEYWORD
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nonn
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AUTHOR
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Emeric Deutsch (deutsch(AT)duke.poly.edu), Jun 28 2005
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