A049000 - OEIS

A049000

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

0, 69, 8082, 820741, 82231803, 8224494757, 822465638000, 82246686892516, 8224670172682646, 822467031614802290, 82246703327412473943, 8224670334073621455209, 822467033422857645316807, 82246703342395510922780776, 8224670334240978188556405240

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,2

COMMENTS

The ratio of successive terms approaches 100.

LINKS

Amiram Eldar, Table of n, a(n) for n = 0..36 (calculated from the b-file at A072692)

FORMULA

a(n) = A072692(n) - A046915(n) ~ Pi^2/12 * 10^(2*n). - Amiram Eldar, Feb 16 2020

EXAMPLE

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.

CROSSREFS

Cf. A000203, A046915.

Cf. A072691 (Pi^2/12).

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

Sequence in context: A364024 A264171 A297550 * A234824 A232719 A297807

Adjacent sequences: A048997 A048998 A048999 * A049001 A049002 A049003

KEYWORD

nonn

AUTHOR

Enoch Haga and Jud McCranie

EXTENSIONS

One more term from Rick L. Shepherd, Jul 03 2002

More terms from Amiram Eldar, Feb 16 2020

STATUS

approved