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Search: id:A080930
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| A080930 |
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Sequence associated with recurrence a(n)=2*a(n-1)+k(k+2)*a(n-2). |
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+0
4
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| 1, 5, 20, 70, 224, 672, 1920, 5280, 14080, 36608, 93184, 232960, 573440, 1392640, 3342336, 7938048, 18677760, 43581440, 100925440, 232128512, 530579456, 1205862400, 2726297600, 6134169600, 13740539904, 30651973632, 68115496960
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OFFSET
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0,2
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COMMENT
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The fourth column of triangle A080928 is 4*A080930.
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FORMULA
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G.f.: (1-x)(1-2x+2x^2)/(1-2x)^4 = (1-3x+4x^2-2x^3)/(1-2x)^4
a(n)=binomial(n+3,3)*2^(n-3), n>=1 - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Oct 29 2006
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MAPLE
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[seq (binomial(n+3, 3)*2^(n-3), n=1..27)]; - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Oct 29 2006
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CROSSREFS
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Sequence in context: A007327 A055403 A089094 this_sequence A000343 A005324 A054889
Adjacent sequences: A080927 A080928 A080929 this_sequence A080931 A080932 A080933
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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), Feb 26 2003
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