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Search: id:A087549
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| A087549 |
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a(1) = 1, a(2) = 1, a(n) =sum of tau(n) previous terms, where tau(n) is the number of divisors of n. |
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+0
1
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| 1, 1, 2, 4, 6, 13, 19, 42, 74, 148, 222, 518, 740, 1628, 3108, 6216, 9324, 21534, 30858, 72668, 134384, 259444, 393828, 928256, 1581528, 3163056, 6066668, 12392780, 18459448, 43245008, 61704456, 145031416, 268440328, 518421208, 993597408
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OFFSET
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1,3
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EXAMPLE
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a(8) = a(4) + a(5) + a(6) + a(7) = 42. tau(8) = 4.
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MAPLE
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with(numtheory): a[1]:=1: a[2]:=1: for n from 3 to 42 do a[n]:=add(a[j], j=n-tau(n)..n-1) od: seq(a[n], n=1..42); (Deutsch)
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CROSSREFS
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Sequence in context: A127105 A110980 A058598 this_sequence A109078 A033305 A105543
Adjacent sequences: A087546 A087547 A087548 this_sequence A087550 A087551 A087552
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KEYWORD
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nonn
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AUTHOR
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Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Sep 13 2003
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EXTENSIONS
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More terms from Emeric Deutsch (deutsch(AT)duke.poly.edu), Mar 27 2005
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