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Search: id:A108639
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| A108639 |
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Sum{k=1 to n} sigma_{n-k}(k), where sigma_m(k) = sum{j|k} j^m. |
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+0
2
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| 1, 3, 6, 13, 29, 77, 229, 771, 2863, 11573, 50365, 234161, 1156039, 6031751, 33130187, 190929778, 1151198268, 7243777234, 47462906927, 323188163753, 2282922216819, 16701529748621, 126359471558613, 987316752551419
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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Row sums of number triangle A109974. - Paul Barry (pbarry(AT)wit.ie), Jul 06 2005
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LINKS
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Leroy Quet, Home Page (listed in lieu of email address)
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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 +1 +8 +1 +9 +1 +2 +4 +1 +1 = 29.
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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->sum(s(i, n-i), i=1..n): seq(a(n), n=1..27); (Deutsch)
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CROSSREFS
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Sequence in context: A018909 A093128 A005313 this_sequence A087218 A098075 A137584
Adjacent sequences: A108636 A108637 A108638 this_sequence A108640 A108641 A108642
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KEYWORD
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nonn
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AUTHOR
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Leroy Quet 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
Edited by N. J. A. Sloane (njas(AT)research.att.com) at the suggestion of Andrew Plewe, Jun 08 2007
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