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Search: id:A067339
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| A067339 |
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Divide the natural numbers in sets of consecutive numbers, starting with {1,2}, each set with number of elements equal to the sum of elements of the preceding set. The final element of the n-th set gives a(n). |
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1
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| 2, 5, 17, 155, 12092, 73114280, 2672849006516342, 3572060905817699556013859788655, 6379809557435582128907282471160505774257452233828787563248842
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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The sets begin {1, 2}, {3, 4, 5}, {6, 7, 8, ..., 17}, ...
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FORMULA
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a(n)=a(n-1)*(a(n-1)+1)/2 + 2
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PROGRAM
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(PARI) a(n) = if(n<2, n=2, a(n-1)*(a(n-1)+1)/2+2)
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CROSSREFS
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Cf. A006894, A002658. Partial sums of A067338.
Sequence in context: A097980 A074046 A123374 this_sequence A096848 A132198 A111635
Adjacent sequences: A067336 A067337 A067338 this_sequence A067340 A067341 A067342
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KEYWORD
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easy,nonn
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AUTHOR
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Floor van Lamoen (fvlamoen(AT)hotmail.com), Jan 16 2002
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EXTENSIONS
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More terms from Jason Earls (zevi_35711(AT)yahoo.com), Jan 16 2002
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