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Search: id:A132912
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| A132912 |
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a(n)=C(n+2,2)(2n)!/2^n. |
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+0
2
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| 1, 3, 36, 900, 37800, 2381400, 209563200, 24518894400, 3677834160000, 687754987920000, 156808137245760000, 42808621468092480000, 13784376112725778560000
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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Define T(n,k)=((1+(-1)^n)/2)*C(k-1+n/2, n/2)*n!/2^(n/2). Then T(n,k) has e.g.f. 1/sum{j=0..k, C(k,j)*(-1)^j*x^(2j)/2^j}. T(n,1) is A000680 with interpolated zeros. T(n,2) is A132911.
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FORMULA
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E.g.f.: 1/(1-(3/2)x^2+(3/4)x^4-(1/8)x^6) (with interpolated zeros);
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CROSSREFS
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Sequence in context: A121245 A122220 A004824 this_sequence A126447 A102921 A102579
Adjacent sequences: A132909 A132910 A132911 this_sequence A132913 A132914 A132915
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KEYWORD
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easy,nonn
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AUTHOR
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Paul Barry (pbarry(AT)wit.ie), Sep 04 2007
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