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A158907
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Row sums of triangle A158906.
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2
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1, 3, 4, 6, 6, 9, 8, 11, 11, 13, 12, 17, 14, 17, 18, 20, 18, 23, 20, 25, 24, 25, 24, 31, 27, 29, 30, 33, 30, 37, 32, 37, 36, 37, 38, 44, 38, 41, 42, 47, 42, 49, 44, 49, 50, 49, 48, 57, 51, 55, 54, 57, 54, 61, 58, 63, 60, 61, 60
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OFFSET
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1,2
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COMMENTS
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This is the number of pairs of positive integers (i,j) such that i*j = n or i+j = n (where (2,2) is double-counted as both 2+2=4 and 2*2=4.) - Peter Kagey, Oct 02 2020
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LINKS
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FORMULA
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a(p) = p + 1 for prime p. [corrected by Ruediger Jehn, Dec 25 2020]
a(n) = Sum_{i=1..n} floor(n/i)-floor((n-1)/(i+1)). - Wesley Ivan Hurt, Sep 13 2017
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EXAMPLE
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a(4) = 6 = (4 + 1 + 0 + 1).
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MAPLE
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end proc:
end proc:
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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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STATUS
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approved
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