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Search: id:A097134
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| 1, 3, 9, 24, 63, 165, 432, 1131, 2961, 7752, 20295, 53133, 139104, 364179, 953433, 2496120, 6534927, 17108661, 44791056, 117264507, 307002465, 803742888, 2104226199, 5508935709, 14422580928, 37758807075, 98853840297, 258802713816
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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Binomial transform of A097133.
Image of 1/(1-3x) under the mapping g(x)->g(x/(1+x^2)) - Paul Barry (pbarry(AT)wit.ie), Jan 16 2005
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FORMULA
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G.f. : (1+x^2)/(1-3x+x^2); a(n)=3a(n-1)-a(n-2), n>2; a(n)=sum{k=0..n, binomial(n, k)(3*F(k)+(-1)^k)}; a(n)=A097135(2n).
a(n)=sum{k=0..floor(n/2), binomial(n-k-1)(-1)^k*3^(n-2k)} - Paul Barry (pbarry(AT)wit.ie), Jan 16 2005
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CROSSREFS
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Cf. A000045.
Sequence in context: A090400 A123888 A166290 this_sequence A123892 A064831 A153582
Adjacent sequences: A097131 A097132 A097133 this_sequence A097135 A097136 A097137
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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), Jul 26 2004
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