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A168013 a(n) = Sum of all divisors of all numbers < (n+1)^2. 3
8, 56, 189, 491, 1007, 1930, 3276, 5314, 8082, 11973, 16783, 23355, 31314, 41380, 53566, 68510, 85771, 106981, 130973, 159470, 192020, 229762, 271873, 320779, 375031, 436311, 504464, 581422, 664364, 759025, 860907, 973989, 1097783 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Partial sums of A168012.

LINKS

Table of n, a(n) for n=1..33.

EXAMPLE

For n=2 the a(2)=56 because the numbers < (2+1)^2 are 1,2,3,4,5,6,7 and 8. Then a(2)= sigma(1))+sigma(2)+sigma(3)+sigma(4)+sigma(5)+sigma(6)+sigma(7)+sigma(8) = 1+3+4+7+6+12+8+15 = 56, where sigma(n) is the sum of divisor of n (see A000203).

CROSSREFS

Cf. A000203, A024916, A168010, A168011, A168012.

Sequence in context: A212817 A267522 A073831 * A003210 A135417 A248332

Adjacent sequences:  A168010 A168011 A168012 * A168014 A168015 A168016

KEYWORD

nonn

AUTHOR

Omar E. Pol, Nov 16 2009

EXTENSIONS

More terms from Sean A. Irvine, Dec 07 2009

STATUS

approved

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Last modified July 23 15:58 EDT 2019. Contains 325258 sequences. (Running on oeis4.)