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A285123
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Min(|d(k+1-i) - d(i)|, for i = 1..k), where d(1),..,d(k) are the divisors of prime(n) - 1.
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1
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0, 1, 0, 1, 3, 1, 0, 3, 9, 3, 1, 0, 3, 1, 21, 9, 27, 4, 5, 3, 1, 7, 39, 3, 4, 0, 11, 51, 3, 6, 5, 3, 9, 17, 33, 5, 1, 9, 81, 39, 87, 3, 9, 4, 0, 7, 1, 31, 111, 7, 21, 3, 1, 15, 0, 129, 63, 3, 11, 6, 41, 69, 1, 21, 11, 75, 7, 5, 171, 17, 6, 177, 55, 19, 3
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OFFSET
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1,5
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LINKS
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FORMULA
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EXAMPLE
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prime(6) - 1 = 12 has divisors 1,2,3,4,6,12, so that k=6 and d(k+1-i) - d(i) ranges through {-11, -4, -1, 1, 4, 11}, so that a(6) = 1.
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MATHEMATICA
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f[n_] := f[n] = Prime[n]-1;
Table[Divisors[f[n]] - Reverse[Divisors[f[n]]], {n, 1, 10}]
Table[Min[Abs[Divisors[f[n]] - Reverse[Divisors[f[n]]]]], {n, 1, 100}]
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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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