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A064947
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Sum_{i|n, j|n, j>i} i.
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1
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0, 1, 1, 4, 1, 10, 1, 11, 5, 12, 1, 36, 1, 14, 14, 26, 1, 43, 1, 45, 16, 18, 1, 96, 7, 20, 18, 53, 1, 107, 1, 57, 20, 24, 20, 153, 1, 26, 22, 123, 1, 128, 1, 69, 65, 30, 1, 224, 9, 73, 26, 77, 1, 148, 24, 147, 28, 36, 1, 374, 1, 38, 77, 120, 26, 168, 1, 93, 32, 165, 1, 411, 1, 44
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,4
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COMMENTS
| For given n, iterate a(n); a(a(n)); a(a(a(n))); ... Does this iterative process allways lead to a(a(...(a(n))...) = 1 ? - Ctibor O. Zizka (ctibor.zizka(AT)seznam.cz), Apr 17 2008
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LINKS
| Harry J. Smith, Table of n, a(n) for n=1,...,1000
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FORMULA
| a(n) = Sum_{i=1..tau(n)} (tau(n)-i)*d_i, where {d_i}, i=1..tau(n), is increasing sequence of divisors of n.
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EXAMPLE
| a(6) = dot_product(3,2,1,0)*(1,2,3,6)=3*1+2*2+1*3+0*6=10.
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MAPLE
| with(numtheory): seq(add((tau(n)-i)*sort(convert(divisors(n), 'list'))[i], i=1..tau(n)), n=1..200);
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PROG
| (PARI) { for (n=1, 1000, d=divisors(n); t=length(d); a=sum(i=1, t - 1, (t - i)*d[i]); write("b064947.txt", n, " ", a) ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), Oct 01 2009]
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CROSSREFS
| Cf. A000005, A000203.
Sequence in context: A176080 A065045 A185088 * A059926 A138775 A121529
Adjacent sequences: A064944 A064945 A064946 * A064948 A064949 A064950
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KEYWORD
| nonn
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AUTHOR
| Vladeta Jovovic (vladeta(AT)eunet.rs), Oct 28 2001
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