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A019565
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If n = Sum 2^e_i, e_i distinct, then a(n) = Product prime_{e_{i+1}}.
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22
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1, 2, 3, 6, 5, 10, 15, 30, 7, 14, 21, 42, 35, 70, 105, 210, 11, 22, 33, 66, 55, 110, 165, 330, 77, 154, 231, 462, 385, 770, 1155, 2310, 13, 26, 39, 78, 65, 130, 195, 390, 91, 182, 273, 546, 455, 910, 1365, 2730, 143, 286, 429, 858, 715, 1430, 2145, 4290
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OFFSET
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0,2
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LINKS
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R. Zumkeller, Table of n, a(n) for n = 0..8191 [From Reinhard Zumkeller, Mar 13 2010]
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FORMULA
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G.f. prod(k>=0, 1 + prime(k+1)*x^2^k), where prime(k)=A000040(k). - Ralf Stephan, Jun 20 2003
a(n) = f(n, 1, 1) with f(x, y, z) = if x > 0 then f(floor(x/2), y*prime(z)^(x mod 2), z+1) else y. [From Reinhard Zumkeller, Mar 13 2010]
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MATHEMATICA
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Do[m=1; o=1; k1=k; While[ k1>0, k2=Mod[k1, 2]; If[k2\[Equal]1, m=m*Prime[o]]; k1=(k1-k2)/ 2; o=o+1]; Print[m], {k, 0, 55}] (Lei Zhou, Feb 15 2005)
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PROG
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(PARI) a(n)=factorback(Mat(vector(#n=vecextract(binary(n), "-1..1"), j, [prime(j), n[j]])~)) \\ - M. F. Hasler, Mar 26 2011
(Haskell)
a019565 n = product $ zipWith (^) a000040_list (a030308_row n)
-- Reinhard Zumkeller, Apr 27 2013
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CROSSREFS
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A101278, A054842. [From Reinhard Zumkeller, Mar 13 2010]
A007088, A030308, A000040.
Sequence in context: A055944 A073740 A077320 * A133477 A039653 A106379
Adjacent sequences: A019562 A019563 A019564 * A019566 A019567 A019568
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KEYWORD
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nonn
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AUTHOR
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Marc LeBrun
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STATUS
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approved
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