

A049030


Sum of sigma(j) for 1<=j<10^n, where sigma(j) = A048050(j) is the sum of the proper divisors >1 of j (excluding 1 and n).


0




OFFSET

1,1


LINKS

Table of n, a(n) for n=1..9.
C. Rivera, Prime Puzzles and Problems Connection


FORMULA

At a(3) = 320243, for example, take a(3) from A049000: 820741  500498 = 320243. Compute 500498 from 999*1000/2 = 499500, split evenly and reverse to 500499  1 = 500498. Add a 9 and 0 for each successive term.


EXAMPLE

For n = 1, the sum of sigma(j), for j < 10 is 0 + 0 + 0 + 2 + 0 + 5 + 0 + 6 + 3 = 16, so a(1) = 16.


CROSSREFS

Cf. A001065, A048050, A048995.
Sequence in context: A221253 A123282 A091160 * A223068 A051551 A289703
Adjacent sequences: A049027 A049028 A049029 * A049031 A049032 A049033


KEYWORD

base,nonn


AUTHOR

Enoch Haga and Jud McCranie


STATUS

approved



