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A125746
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a(n) = smallest divisor d of n such that n <= {sum of d and all smaller divisors of n}.
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5
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1, 2, 3, 4, 5, 3, 7, 8, 9, 10, 11, 6, 13, 14, 15, 16, 17, 9, 19, 10, 21, 22, 23, 8, 25, 26, 27, 14, 29, 15, 31, 32, 33, 34, 35, 12, 37, 38, 39, 20, 41, 21, 43, 44, 45, 46, 47, 16, 49, 50, 51, 52, 53, 27, 55, 28, 57, 58, 59, 20, 61, 62, 63, 64, 65, 33, 67, 68, 69, 35, 71, 24, 73
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OFFSET
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1,2
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COMMENTS
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Original name of this sequence: a(n) is the smallest positive integer such that (sum{k|n, 1<=k<=a(n)} k) is >= n.
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LINKS
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EXAMPLE
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The divisors of 12 are 1,2,3,4,6,12. 1+2+3+4 = 10, which is smaller than 12; but 1+2+3+4+6 = 16, which is >= 12. So a(12) = 6.
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MATHEMATICA
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f[n_] := Block[{k = 1, d = Divisors[n]}, While[Sum[d[[i]], {i, k}] < n, k++ ]; d[[k]]]; Table[f[n], {n, 76}] (* Ray Chandler, Dec 06 2006 *)
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PROG
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(PARI) A125746(n) = { my(k=0, s=0); fordiv(n, d, k++; s += d; if(s>=n, return(d))); }; \\ Antti Karttunen, Mar 21 2018
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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