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Search: id:A090040
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| 1, 5, 28, 164, 976, 5840, 35008, 209984, 1259776, 7558400, 45349888, 272098304, 1632587776, 9795522560, 58773127168, 352638746624, 2115832446976, 12694994616320, 76169967566848, 457019805138944, 2742118830309376
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OFFSET
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0,2
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FORMULA
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G.f. : (1-3x)/((1-2x)(1-6x)); E.g.f.: (3exp(6x)+exp(2x))/4=exp(4x)(cosh(2x)+sinh(2x)/2); a(n)=8a(n-1)-12a(n-2), a(0)=1, a(1)=5; a(n)=(3*6^n+2^n)/4.
Fourth binomial transform of (1, 1, 4, 4, 16, 16, ...). a(n)=sum{k=1..floor(n/2), C(n, 2k)4^(n-k-1)}. - Paul Barry (pbarry(AT)wit.ie), Nov 22 2003
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CROSSREFS
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Cf. A081335.
Adjacent sequences: A090037 A090038 A090039 this_sequence A090041 A090042 A090043
Sequence in context: A015536 A005785 A027912 this_sequence A025174 A083316 A027284
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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), Nov 20 2003
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