OFFSET
1,1
LINKS
Wikipedia, Multiply perfect number
Wikipedia, Harmonic divisor number.
EXAMPLE
a(1) = 672 is the smallest number k that is both an Ore number and multiperfect such that sigma(k)/k > 2.
MATHEMATICA
Module[{a166069 = {120, 672, 30240, 32760, 523776, 2178540, 23569920, 45532800, 142990848, 459818240, 1379454720}, i, n, result = {}}, For[i = 1, i <= Length[a166069], i++, n = a166069[[i]]; If[Mod[DivisorSigma[0, n], DivisorSigma[-1, n]] == 0, AppendTo[result, n]]]; result]
CROSSREFS
KEYWORD
nonn
AUTHOR
David Terr, Jan 24 2021
EXTENSIONS
Name changed by and more terms from Jinyuan Wang, Feb 11 2021
STATUS
approved