A049000 - OEIS

%I #24 Feb 16 2020 03:19:10

%S 0,69,8082,820741,82231803,8224494757,822465638000,82246686892516,

%T 8224670172682646,822467031614802290,82246703327412473943,

%U 8224670334073621455209,822467033422857645316807,82246703342395510922780776,8224670334240978188556405240

%N Sum of sigma(j) for 1<=j<10^n, where sigma(j) is the sum of divisors of j.

%C The ratio of successive terms approaches 100.

%H Amiram Eldar, <a href="/A049000/b049000.txt">Table of n, a(n) for n = 0..36</a> (calculated from the b-file at A072692)

%F a(n) = A072692(n) - A046915(n) ~ Pi^2/12 * 10^(2*n). - _Amiram Eldar_, Feb 16 2020

%e For n=1, the sum of sigma(j) for j<10 is 1+3+4+7+6+12+8+15+13=69, so a(1)=69.

%Y Cf. A000203, A046915.

%Y Cf. A072691 (Pi^2/12).

%Y Cf. A072692 (sum for 1<=j<=10^n and other links).

%K nonn

%O 0,2

%A _Enoch Haga_ and _Jud McCranie_

%E One more term from _Rick L. Shepherd_, Jul 03 2002

%E More terms from _Amiram Eldar_, Feb 16 2020