OFFSET
1,2
COMMENTS
In the case of a tie, we round up. - Robert Israel, May 26 2019
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
FORMULA
a(n) = n*floor((floor(n/2)+sigma(n))/n).
EXAMPLE
n=100: sigma[100]=217 is between 100=1.100 and 200=2.100
200 is closer to 217, so a[100]=200;
MAPLE
f:= proc(n) uses numtheory; n*floor((floor(n/2)+sigma(n))/n) end proc:
map(f, [$1..100]); # Robert Israel, May 26 2019
MATHEMATICA
Table[n*Floor[(Floor[n/2]+DivisorSigma[1, n])/n], {n, 1, 100}]
PROG
(PARI) a(n)=sigma(n)\/n*n \\ Charles R Greathouse IV, Feb 15 2013
CROSSREFS
KEYWORD
nonn,look
AUTHOR
Labos Elemer, Apr 22 2003
STATUS
approved