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Search: id:A108699
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| A108699 |
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Product{k=1 to n} sigma_{n-k+1}(k), where sigma_m(k) = sum{j|k} j^m. |
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+0
1
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| 1, 3, 20, 630, 59976, 61631856, 218220912000, 11776702254660000, 3875704211027805137280, 16098074199800249059584941760, 426743858218976407063631274998400000
(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) = 1^5 * (1^4 +2^4) * (1^3 +3^3) * (1^2 +2^2 +4^2) * (1^1 +5^1) =
1 * 17 * 28 * 21 * 6 = 59976.
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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+1), i=1..n): seq(a(n), n=1..13); (Deutsch)
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CROSSREFS
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Adjacent sequences: A108696 A108697 A108698 this_sequence A108700 A108701 A108702
Sequence in context: A003150 A138897 A089943 this_sequence A002857 A024011 A052445
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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 07 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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