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A104076
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If k(m) is the m-th divisor (when the divisors are ordered by size) of n, then a(n) = gcd(k(1)+k(2), k(2)+k(3), k(3)+k(4), ..., k(j-1)+k(j)), where j is the number of divisors of n.
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1
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3, 4, 3, 6, 1, 8, 3, 4, 1, 12, 1, 14, 3, 4, 3, 18, 1, 20, 3, 2, 1, 24, 1, 6, 3, 4, 1, 30, 1, 32, 3, 2, 1, 6, 1, 38, 3, 4, 1, 42, 1, 44, 3, 2, 1, 48, 1, 8, 1, 4, 1, 54, 1, 2, 1, 2, 1, 60, 1, 62, 3, 2, 3, 6, 1, 68, 3, 2, 1, 72, 1, 74, 3, 4, 1, 2, 1, 80, 1, 4, 1, 84, 1, 2, 3, 4, 1, 90, 1, 4, 3, 2, 1, 6, 1, 98
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OFFSET
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2,1
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LINKS
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Harvey P. Dale, Table of n, a(n) for n = 2..1000
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EXAMPLE
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The divisors of 14 are 1,2,7,14. So a(14) = gcd(1+2, 2+7, 7+14) = 3.
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MAPLE
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A104076 := proc(n) local dvs ; dvs := sort(convert(numtheory[divisors](n), list)) ; igcd(seq( op(i, dvs)+op(i+1, dvs), i=1..nops(dvs)-1)) ; end: for n from 2 to 140 do printf("%d, ", A104076(n)) ; od: # R. J. Mathar, Sep 05 2008
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MATHEMATICA
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Table[GCD@@(Total/@Partition[Divisors[n], 2, 1]), {n, 2, 100}] (* Harvey P. Dale, Dec 18 2018 *)
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CROSSREFS
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Cf. A143771.
Sequence in context: A045997 A262150 A325594 * A238161 A332880 A281626
Adjacent sequences: A104073 A104074 A104075 * A104077 A104078 A104079
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KEYWORD
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nonn
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AUTHOR
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Leroy Quet, Aug 31 2008
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EXTENSIONS
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Extended by R. J. Mathar, Sep 05 2008
Definition corrected by Leroy Quet, Sep 21 2008
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STATUS
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approved
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