A046914 Sum of aliquot factors (divisors excluding the number itself) of 10^n.

0, 8, 117, 1340, 14211, 146078, 1480437, 14902280, 149511591, 1497558338, 14987792457, 149938963820, 1499694822171, 14998474116998, 149992370597277, 1499961853010960, 14999809265103951, 149999046325618058, 1499995231628286897

Offset

0,2

Links

Table of n, a(n) for n=0..18.

Formula

a(n) = A001065(10^n). - Michel Marcus, Jul 24 2015

a(n) = (2^(n+1)-1)*(5^(n+1)-1)/4 - 10^n. - Giovanni Resta, Jul 24 2015

Example

The aliquot factors of 10^1 are 1, 2 and 5; 10 is not counted, so 1 + 2 + 5 = 8.

Mathematica

Table[DivisorSum[x = 10^n, # &, # != x &], {n, 0, 18}] (* Jayanta Basu, Jun 30 2013 *)

Prog

(PARI) vector(20, n, n--; sigma(10^n) - 10^n) \\ Michel Marcus, Jul 24 2015

Crossrefs

Cf. A001065.

Sequence in context: A291077 A056988 A085699 * A376124 A364984 A341197

Adjacent sequences: A046911 A046912 A046913 * A046915 A046916 A046917

Keyword

easy,nonn

Author

Enoch Haga

Status

approved