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A098221
a(n) is the smallest number x such that floor(sigma(sigma(x))/x) = n or the A098219(x) quotient equals n.
5
1, 2, 8, 6, 40, 30, 24, 60, 120, 480, 540, 1560, 2520, 10920, 27720, 30240, 191520, 524160, 360360, 3243240, 5765760, 28828800, 109549440, 438197760, 766846080, 3834230400, 9081072000, 32974381440, 147516969600, 880887047040, 2802822422400
OFFSET
1,2
COMMENTS
a(30) <= 880887047040. a(31) <= 2802822422400. - Donovan Johnson, Feb 16 2013
FORMULA
a(n) = Min{x;floor(A051027(x)/x)=n)
EXAMPLE
n = 10: a(10) = 480 because floor(sigma(sigma(480))/480) = floor(sigma(1512)/480) = floor(4800/480) = 4800/480 = n = 10.
MATHEMATICA
t=Table[0, {100}]; Do[s=g[n]; If[s<101&&t[[s]]==0, t[[s]]=n], {n, 1, 1000000}]; t
KEYWORD
nonn,more
AUTHOR
Labos Elemer, Oct 25 2004
EXTENSIONS
a(20)-a(26) from Donovan Johnson, Dec 29 2008
a(27)-a(29) from Donovan Johnson, Feb 16 2013
a(30)-a(31) from Giovanni Resta, Feb 27 2020
STATUS
approved