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A093468
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a(1) = 1, a(2) = 2; for n >= 2, a(n+1) = a(n) + Sum {a(n)-a(i), i = 1 to n}.
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2
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1, 2, 3, 6, 18, 78, 438, 2958, 23118, 204558, 2018958, 21977358, 261478158, 3374988558, 46964134158, 700801318158, 11162196262158, 189005910310158, 3390192763174158, 64212742967590158, 1280663747055910158
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OFFSET
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1,2
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COMMENTS
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LINKS
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FORMULA
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a(n)=n*a(n-1)-(n-1)*a(n-2), n>3. - Gary Detlefs, Dec 30 2010
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MATHEMATICA
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a[1] = 1; a[2] = 2; a[n_] := a[n] = a[n - 1] + Sum[a[n - 1] - a[i], {i, n - 1}]; Table[ a[n], {n, 21}] (* Robert G. Wilson v, Apr 08 2004 *)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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