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A337933
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Numbers that are the sum of two abundant numbers in exactly one way.
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0
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24, 30, 32, 38, 40, 44, 50, 52, 56, 58, 62, 64, 70, 957, 963, 965, 969, 975, 981, 985, 987, 993, 999, 1001, 1005, 1011, 1015, 1017, 1023, 1025, 1029, 1033, 1035, 1041, 1045, 1047, 1049, 1053, 1057, 1059, 1065, 1071, 1077, 1083, 1085, 1089, 1095, 1101, 1105, 1107, 1113
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OFFSET
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1,1
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COMMENTS
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An easy to calculate upper bound for terms is 12*(A047802(2)+1) = 64696932312. This and all larger numbers can be expressed as the sum of an abundant multiple of 6 and a multiple of A047802(2) in at least two ways. - Peter Munn, Feb 09 2021
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LINKS
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EXAMPLE
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24 is in the sequence since it is the sum of two abundant numbers in exactly one way as 24 = 12 + 12.
30 is in the sequence since it is the sum of two abundant numbers in exactly one way as 30 = 12 + 18.
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MATHEMATICA
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Table[If[Sum[(1 - Sign[Floor[(2 (n - i))/DivisorSigma[1, n - i]]])*(1 - Sign[Floor[(2 i)/DivisorSigma[1, i]]]), {i, Floor[n/2]}] == 1, n, {}], {n, 1200}] // Flatten
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CROSSREFS
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KEYWORD
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nonn,fini
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AUTHOR
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STATUS
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approved
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