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Search: id:A067353
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| A067353 |
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Divide the natural numbers in sets of consecutive numbers starting with {1,2} as the first set. The number of elements of the n-th set is equal to the sum of the n-1 final numbers in the (n-1)st set. The final number of the n-th set gives a(n). |
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+0
2
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| 2, 4, 11, 41, 199, 1184, 8273, 66163, 595439, 5954354, 65497849, 785974133, 10217663663, 143047291204, 2145709367969, 34331349887399, 583632948085663
(list; graph; listen)
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OFFSET
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1,1
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FORMULA
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a(n)=n*a(n-1)-(n-1)(n-2)/2 with a(1)=2. a(n)=b(1)+b(2)+...+b(n) with b(n) as in A067352.
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EXAMPLE
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The sets begin {1,2},{3,4},{5,6,...,9,10,11},{12,13,...,38,39,40,41},...
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CROSSREFS
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Sequence in context: A013182 A013170 A099934 this_sequence A105996 A107703 A114954
Adjacent sequences: A067350 A067351 A067352 this_sequence A067354 A067355 A067356
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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 17 2002
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