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A289274
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Numbers k such that the deficiency of k^2 is itself a square > 1.
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3
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46, 284, 1633, 149728, 242656, 260495, 298057, 1056752, 9587584, 17706256, 914429696, 985501822, 1074266048, 1484820224, 4241800921, 12147056128, 109548719577, 287291764736, 360499817799
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OFFSET
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1,1
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COMMENTS
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The sequence of square roots of the deficiencies of this sequence is A288144.
The disjoint union of the current sequence with the powers of 2 (A000079) is A289275, the sequence of numbers k for which the deficiency of k^2 is a square (including 1).
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LINKS
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EXAMPLE
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The deficiency of 46^2 is 2*46^2 - sigma(46^2) = 19^2, so 46 is a term of the sequence.
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MAPLE
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issq := n -> evalb(n>1 and issqr(n)):
A033879 := n -> 2*n - numtheory[sigma](n):
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PROG
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(PARI) isok(n) = issquare(d = 2*n^2 - sigma(n^2)) && (d!=1); \\ Michel Marcus, Jul 25 2017
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CROSSREFS
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KEYWORD
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nonn,more
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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