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Search: id:A108640
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| A108640 |
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Product{k=1 to n} sigma_{n-k}(k), where sigma_m(k) = sum{j|k} j^m. |
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1
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| 1, 2, 6, 60, 1260, 239904, 123263712, 872883648000, 35330106763980000, 15502816844111220549120, 32196148399600498119169883520, 2560463149313858442381787649990400000, 717635502576022020068175045395317927056000000
(list; graph; listen)
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OFFSET
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1,2
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EXAMPLE
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a(5) = 1^4 * (1^3 +2^3) * (1^2 +3^2) * (1^1 +2^1 +4^1) * (1^0 +5^0) = 1 * 9 * 10 * 7 * 2 = 1260.
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MAPLE
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with(numtheory): s:=proc(n, k) local div: div:=divisors(n): sum(div[j]^k, j=1..tau(n)) end: a:=n->product(s(i, n-i), i=1..n): seq(a(n), n=1..14); (Deutsch)
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CROSSREFS
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Sequence in context: A056604 A086332 A089039 this_sequence A084971 A001577 A077175
Adjacent sequences: A108637 A108638 A108639 this_sequence A108641 A108642 A108643
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KEYWORD
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nonn
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AUTHOR
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Leroy Quet (qq-quet(AT)mindspring.com), Jul 06 2005
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EXTENSIONS
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More terms from Emeric Deutsch (deutsch(AT)duke.poly.edu), Jul 13 2005
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