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A136528
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a(n) = the highest possible number of positive divisors of the sum of any two distinct positive divisors of n.
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1
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2, 3, 4, 4, 4, 4, 6, 6, 6, 6, 6, 4, 5, 6, 8, 6, 8, 6, 8, 8, 8, 8, 9, 8, 6, 9, 8, 8, 9, 6, 10, 9, 9, 9, 10, 4, 8, 8, 12, 8, 10, 6, 10, 12, 10, 10, 12, 8, 12, 8, 8, 8, 12, 12, 12, 12, 12, 12, 12, 4, 7, 12, 12, 8, 12, 6, 12, 12, 12, 12, 12, 4, 6, 12, 10, 12, 12, 10, 16, 12, 12, 12, 12, 12, 8, 12, 12, 12, 16, 8, 12, 12, 12, 12, 16
(list; graph; refs; listen; history; internal format)
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OFFSET
| 2,1
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COMMENTS
| There are d(n)*(d(n)-1)/2 sums of pairs of distinct positive divisors of n, where d(n) = number of positive divisors of n.
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EXAMPLE
| The positive divisors of 6 are 1,2,3,6. Letting d(m) = the number of positive divisors of m: d(1+2)=2; d(1+3)=3; d(1+6)=2; d(2+3)=2; d(2+6)=4; d(3+6)=3. The maximum of these values is 4, so a(6) = 4.
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CROSSREFS
| Cf. A136529.
Sequence in context: A064004 A195849 A087827 * A130242 A130245 A087793
Adjacent sequences: A136525 A136526 A136527 * A136529 A136530 A136531
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KEYWORD
| nonn
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AUTHOR
| Leroy Quet Jan 03 2008
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EXTENSIONS
| More terms from Sean A. Irvine (sairvin(AT)xtra.co.nz), Feb 28 2011
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