

A136363


a(n) = Sum_{ composite k, 1 <= k <= 10^n} (Sum of divisors d of k with 1 < d < k).


1



23, 3150, 321582, 32241015, 3224590836, 322466618438, 32246696794797, 3224670272194238, 322467032612360629, 32246703337400266401, 3224670334173560419030, 322467033423857340138979
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OFFSET

1,1


LINKS

Table of n, a(n) for n=1..12.


FORMULA

a(n) = A072692(n)  10^n*(10^n+3)/2 + 1 [From Max Alekseyev, May 10 2009]


EXAMPLE

a(1)=23 because the divisors through 10^1 are as follows: 4 (2); 6 (2,3); 8 (2,4); 9 (3); 10 (2,5). The sum is 2+2+3+2+4+3+2+5=23.


CROSSREFS

Cf. A136364.
Sequence in context: A030461 A152521 A267692 * A290786 A248335 A222031
Adjacent sequences: A136360 A136361 A136362 * A136364 A136365 A136366


KEYWORD

easy,nonn


AUTHOR

Enoch Haga, Dec 26 2007, Dec 29 2007


EXTENSIONS

Edited by N. J. A. Sloane, Jan 12 2008
Extended by Max Alekseyev, May 10 2009


STATUS

approved



