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Search: id:A064945
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| A064945 |
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Sum_{i|n, j|n, j >= i} i. |
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+0
1
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| 1, 4, 5, 11, 7, 22, 9, 26, 18, 30, 13, 64, 15, 38, 38, 57, 19, 82, 21, 87, 48, 54, 25, 156, 38, 62, 58, 109, 31, 179, 33, 120, 68, 78, 68, 244, 39, 86, 78, 213, 43, 224, 45, 153, 143, 102, 49, 348, 66, 166, 98, 175, 55, 268, 96, 267, 108, 126, 61, 542, 63, 134, 181
(list; graph; listen)
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OFFSET
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1,2
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FORMULA
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a(n) = Sum_{i=1..tau(n)} (tau(n)-i+1)*d_i, where {d_i}, i=1..tau(n), is increasing sequence of divisors of n.
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EXAMPLE
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a(6) = dot_product(4,3,2,1)*(1,2,3,6)=4*1+3*2+2*3+1*6=22.
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MAPLE
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with(numtheory): seq(add((tau(n)-i+1)*sort(convert(divisors(n), 'list'))[i], i=1..tau(n)), n=1..200);
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CROSSREFS
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Cf. A000005, A000203, A060640.
Sequence in context: A126069 A147559 A007429 this_sequence A069820 A027708 A047374
Adjacent sequences: A064942 A064943 A064944 this_sequence A064946 A064947 A064948
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KEYWORD
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nonn
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AUTHOR
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Vladeta Jovovic (vladeta(AT)Eunet.yu), Oct 28 2001
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