A188263 Odd abundant numbers whose abundancy is closer to 2 than any smaller odd abundant number.

945, 2205, 7425, 8415, 8925, 31815, 32445, 351351, 442365, 14571585, 20355825, 20487159, 78524145, 159030135, 1756753845, 2586415095, 82014476355, 93128205975, 125208115065, 127595519865, 154063853475, 394247024535, 948907364895

Offset: 1

Author

T. D. Noe, Mar 30 2011

Keywords

• nonn

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)

Crossrefs

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

Programs

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}]

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