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A087247
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Squarefree deficient nonprime numbers.
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4
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1, 10, 14, 15, 21, 22, 26, 33, 34, 35, 38, 39, 46, 51, 55, 57, 58, 62, 65, 69, 74, 77, 82, 85, 86, 87, 91, 93, 94, 95, 105, 106, 110, 111, 115, 118, 119, 122, 123, 129, 130, 133, 134, 141, 142, 143, 145, 146, 154, 155, 158, 159, 161, 165, 166, 170, 177, 178, 182, 183
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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LINKS
| Enrique Pérez Herrero, Table of n, a(n) for n = 1..10000
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EXAMPLE
| m=105=3.5.7 and sigma[105]=1+3+5+7+15+21+35+105=192<210=2m.
The sequence differs from A006881: first number
with 3 distinct prime factors is 105.
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MATHEMATICA
| isA087247[n_] := SquareFreeQ[n] && !PrimeQ[n] && (DivisorSigma[1, n] < 2n); Select[Range[200], isA087247] (* From Enrique Pérez Herrero, Jan 13 2011 *)
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CROSSREFS
| Cf. A087244-A087248, A008683, A000203, A013929, A005117, A005100, A005101.
Sequence in context: A036338 A108793 A100929 * A171156 A088711 A154774
Adjacent sequences: A087244 A087245 A087246 * A087248 A087249 A087250
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KEYWORD
| nonn
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AUTHOR
| Labos E. (labos(AT)ana.sote.hu), Sep 05 2003
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