A188263 - OEIS

%I #34 Mar 31 2013 15:57:52

%S 945,2205,7425,8415,8925,31815,32445,351351,442365,14571585,20355825,

%T 20487159,78524145,159030135,1756753845,2586415095,82014476355,

%U 93128205975,125208115065,127595519865,154063853475,394247024535,948907364895

%N Odd abundant numbers whose abundancy is closer to 2 than any smaller odd abundant number.

%C 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.

%C 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.

%C These are odd numbers that are barely abundant. See A071927 for the even version.

%C a(24) > 10^12. - _Donovan Johnson_, May 05 2012

%H Giovanni Resta, <a href="/A188263/b188263.txt">Table of n, a(n) for n = 1..31</a> (terms < 10^13)

%t 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}]

%Y Cf. A171929 (odd numbers whose abundancy is closer to 2 than any smaller odd number)

%K nonn

%O 1,1

%A _T. D. Noe_, Mar 30 2011

%E a(15)-a(16) from _Donovan Johnson_, Mar 31 2011

%E a(17)-a(22) from _Donovan Johnson_, Apr 02 2011

%E a(23) from _Donovan Johnson_, May 05 2012