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A067352
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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 number of elements of the n-th set gives a(n).
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1
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2, 2, 7, 30, 158, 985, 7089, 57890, 529276, 5358915, 59543495, 720476284, 9431689530, 132829627541, 2002662076765, 32185640519430, 549301598198264
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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FORMULA
| a(n) = (1+a(1)+a(2)+...+a(n-1)-n/2)*(n-1).
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EXAMPLE
| The sets begin {1,2},{3,4},{5,6,...,9,10,11},{12,13,...,38,39,40,41},...
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CROSSREFS
| Cf. A067353.
Sequence in context: A069101 A138802 A047003 * A062448 A139523 A079242
Adjacent sequences: A067349 A067350 A067351 * A067353 A067354 A067355
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KEYWORD
| easy,nonn
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AUTHOR
| Floor van Lamoen (fvlamoen(AT)hotmail.com), Jan 17 2002
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