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A067338
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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 number of elements in the n-th set gives a(n).
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1
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OFFSET
| 1,1
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COMMENTS
| The sets begin {1,2},{3,4,5},{6,7,8,...,17},...
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FORMULA
| a(n)=(1+2*[a(1)+a(2)+...+a(n-2)]+a(n-1))*a(n-1)
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CROSSREFS
| Sequence in context: A162075 A102878 A132501 * A012713 A009814 A196378
Adjacent sequences: A067335 A067336 A067337 * A067339 A067340 A067341
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KEYWORD
| easy,nonn
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AUTHOR
| Floor van Lamoen (fvlamoen(AT)hotmail.com), Jan 16 2002
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