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Search: id:A058359
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| A058359 |
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Absolute value of difference between the even and odd first differences of the divisors of n. |
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+0
1
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| 0, 1, 2, 1, 4, 5, 6, 5, 8, 9, 10, 5, 12, 13, 14, 13, 16, 17, 18, 5, 20, 21, 22, 17, 24, 25, 26, 5, 28, 17, 30, 29, 32, 33, 34, 17, 36, 37, 38, 29, 40, 41, 42, 5, 44, 45, 46, 41, 48, 49, 50, 5, 52, 53, 54, 45, 56, 57, 58, 33, 60, 61, 62, 61, 64, 65, 66, 5, 68, 57, 70, 57, 72, 73, 74
(list; graph; listen)
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OFFSET
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1,3
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EXAMPLE
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The divisors of twelve are {1, 2, 3, 4, 6 and 12}, the first difference is {1, 1, 1, 2 and 6}. The even differences add up to 8 while the odd differences add up to 3. The absolute difference between the even and odd first differences of 12 therefore is 5.
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MATHEMATICA
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f[ n_Integer ] := (d = Divisors[ n ]; l = Length[ d ]; s = 0; i = 1; While[ i < l, e = d[ [ i + 1 ] ] - d[ [ i ] ]; If[ EvenQ[ e ], s = s + e, s = s - e ]; i++ ]; Abs[ s ]); Table[ f[ n ], {n, 1, 75} ]
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CROSSREFS
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Sequence in context: A075423 A144774 A074720 this_sequence A110332 A159287 A052947
Adjacent sequences: A058356 A058357 A058358 this_sequence A058360 A058361 A058362
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KEYWORD
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nonn
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AUTHOR
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Robert G. Wilson v (rgwv(AT)rgwv.com), Dec 16 2000
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