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Search: id:A034689
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| A034689 |
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One half of sextic factorial numbers. |
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+0
13
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| 1, 8, 112, 2240, 58240, 1863680, 70819840, 3116072960, 155803648000, 8725004288000, 540950265856000, 36784618078208000, 2722061737787392000, 217764939022991360000, 18727784755977256960000
(list; graph; listen)
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OFFSET
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1,2
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FORMULA
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2*a(n) = (6*n-4)(!^6) := product(6*j-4, j=1..n) = 2^n*A007559(n), A007559(n)=(3*n-2)(!^3) := product(3*j-2, j=1..n); E.g.f. (-1+(1-6*x)^(-1/3))/2.)
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MATHEMATICA
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s=1; lst={s}; Do[s+=n*s; AppendTo[lst, s], {n, 7, 5!, 6}]; lst [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Nov 08 2008]
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CROSSREFS
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Cf. A008542, A007559.
Sequence in context: A139741 A067900 A067414 this_sequence A010041 A099703 A164774
Adjacent sequences: A034686 A034687 A034688 this_sequence A034690 A034691 A034692
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KEYWORD
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easy,nonn
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AUTHOR
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Wolfdieter Lang (wolfdieter.lang(AT)physik.uni-karlsruhe.de)
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