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A106847 Sum {k + lm <= n} (k + lm), with 0 < k,l,m <= n. 4
0, 0, 2, 11, 31, 71, 131, 229, 357, 537, 767, 1064, 1412, 1867, 2385, 3000, 3720, 4570, 5506, 6608, 7808, 9194, 10734, 12436, 14260, 16360, 18622, 21079, 23739, 26668, 29758, 33199, 36815, 40742, 44924, 49369, 54085, 59265, 64661, 70355 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

M. F. Hasler, Table of n, a(n) for n = 0..9999

EXAMPLE

We have 1+1*1=2<=3, 1+2*1=3, 1+1*2=3, 2+1*1=3, thus a(3)=2+3+3+3=11.

MAPLE

A106847 := proc(n)

    local a, k, l, m ;

    a := 0 ;

    for k from 1 to n do

        for l from 1 to n-k do

            m := floor((n-k)/l) ;

            if m >=1 then

                m := min(m, n) ;

                a := a+m*k+l*m*(m+1)/2 ;

            end if;

        end do:

    end do:

    a ;

end proc: # R. J. Mathar, Oct 17 2012

PROG

(PARI) A106847(n)=sum(m=1, n-1, sum(k=1, (n-1)\m, (n-m*k)*(n+m*k+1)))/2  \\ - M. F. Hasler, Oct 17 2012

CROSSREFS

Cf. A106633, A106634, A106846, A078567 (number of terms).

Sequence in context: A085041 A197642 A121346 * A092761 A296733 A087933

Adjacent sequences:  A106844 A106845 A106846 * A106848 A106849 A106850

KEYWORD

nonn

AUTHOR

Ralf Stephan, May 06 2005

STATUS

approved

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Last modified June 18 17:05 EDT 2019. Contains 324214 sequences. (Running on oeis4.)