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

1,1

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

Adjacent sequences: A188260 A188261 A188262 * A188264 A188265 A188266

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