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Search: id:A067340
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| A067340 |
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Number of prime factors divided by the number of distinct prime factors is an integer. |
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+0
9
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| 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 14, 15, 16, 17, 19, 21, 22, 23, 24, 25, 26, 27, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 46, 47, 49, 51, 53, 54, 55, 56, 57, 58, 59, 61, 62, 64, 65, 66, 67, 69, 70, 71, 73, 74, 77, 78, 79, 81, 82, 83, 85, 86, 87, 88, 89, 91
(list; graph; listen)
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OFFSET
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1,1
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FORMULA
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A001222(n)/A001221(n) is integer
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EXAMPLE
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Primes and prime-powers are included here. Another example: 24, since A001222(24)/A001222(24)=4/2=2.
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MATHEMATICA
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ff[x_] := Flatten[FactorInteger[x]] f1[x_] := Length[FactorInteger[x]] f2[x_] := Apply[Plus, Table[Part[ff[x], 2*w], {w, 1, f1[x]}]] Do[s=f2[n]/f1[n]; If[IntegerQ[s], Print[n]], {n, 2, 256}]
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PROGRAM
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(PARI) v=[]; for(n=2, 100, if(denominator(bigomega(n)/omega(n)) == 1, v=concat(v, n))); v
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CROSSREFS
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Cf. A001221, A001222.
Sequence in context: A053460 A065200 A107909 this_sequence A085924 A072774 A062770
Adjacent sequences: A067337 A067338 A067339 this_sequence A067341 A067342 A067343
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KEYWORD
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nonn
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AUTHOR
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Labos E. (labos(AT)ana.sote.hu), Jan 16 2002
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