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A188263 Odd abundant numbers whose abundancy is closer to 2 than any smaller odd abundant number. 10
945, 2205, 7425, 8415, 8925, 31815, 32445, 351351, 442365, 14571585, 20355825, 20487159, 78524145, 159030135, 1756753845, 2586415095, 82014476355, 93128205975, 125208115065, 127595519865, 154063853475, 394247024535, 948907364895 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
The abundancy of a number n is defined as sigma(n)/n. Abundant numbers have an abundancy greater than 2. All these numbers must be odd primitive abundant numbers, A006038.
These numbers might be considered the opposite of A119239, which has odd numbers whose abundancy increases. This sequence has terms in common with A171929. A similar sequence for deficient numbers is A188597.
These are odd numbers that are barely abundant. See A071927 for the even version.
a(24) > 10^12. - Donovan Johnson, May 05 2012
LINKS
Giovanni Resta, Table of n, a(n) for n = 1..31 (terms < 10^13)
MATHEMATICA
k = 1; minDiff = 1; Table[k = k + 2; While[abun = DivisorSigma[1, k]/k; abun - 2 > minDiff || abun < 2, k = k + 2]; minDiff = abun - 2; k, {10}]
CROSSREFS
Cf. A171929 (odd numbers whose abundancy is closer to 2 than any smaller odd number)
Sequence in context: A275066 A127667 A252184 * A188342 A109729 A294025
KEYWORD
nonn
AUTHOR
T. D. Noe, Mar 30 2011
EXTENSIONS
a(15)-a(16) from Donovan Johnson, Mar 31 2011
a(17)-a(22) from Donovan Johnson, Apr 02 2011
a(23) from Donovan Johnson, May 05 2012
STATUS
approved

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Last modified July 14 05:06 EDT 2024. Contains 374291 sequences. (Running on oeis4.)