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A053869
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Sum of divisors of n less than n is even.
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6
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1, 6, 9, 10, 12, 14, 20, 22, 24, 25, 26, 28, 30, 34, 38, 40, 42, 44, 46, 48, 49, 52, 54, 56, 58, 60, 62, 66, 68, 70, 74, 76, 78, 80, 81, 82, 84, 86, 88, 90, 92, 94, 96, 102, 104, 106, 108, 110, 112, 114, 116, 118, 120, 121, 122, 124, 126, 130, 132, 134, 136, 138, 140
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OFFSET
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1,2
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COMMENTS
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Numbers which if odd are squares and which if even are neither squares nor twice squares.
Numbers whose sum of proper divisors is even. - Omar E. Pol, Aug 14 2009
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LINKS
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FORMULA
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PROG
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(Haskell)
a053869 n = a053869_list !! (n-1)
a053869_list = filter (even . a001065) [1..]
a053869_list = map (+ 1) $ findIndices even $ map a001065 [1..]
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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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