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A192818
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Numbers which are both deficient (A005100) and anti-deficient (A192267).
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2
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1, 2, 3, 4, 9, 16, 19, 26, 29, 34, 44, 51, 61, 64, 69, 79, 89, 106, 131, 134, 139, 141, 146, 159, 166, 169, 191, 194, 201, 209, 211, 219, 226, 236, 239, 244, 251, 254, 261, 271, 274, 289, 296, 299, 309, 316, 321, 334, 339, 341, 344, 349, 359, 376, 381, 386
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OFFSET
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1,2
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LINKS
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FORMULA
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EXAMPLE
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24 is anti-deficient because its anti-divisors are 7, 16 and their sum is 23 < 24. 26 is deficient because its proper divisors are 1, 2, 13 which sum to 16 and 16 < 26.
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MATHEMATICA
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q[n_] := Total[Cases[Range[2, n - 1], _?(Abs[Mod[n, #] - #/2] < 1 &)]] < n && DivisorSigma[1, n] < 2*n; Select[Range[300], q] (* Amiram Eldar, Jan 13 2022 after Michael De Vlieger at A066417 *)
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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